It may help to know a bit more about what your end goal with this transfer project is...
Is this just for personal enjoyment listening?
Personally speaking, I'm of the mindset that the record should be listened to as it was intended. I don't need to reduce the DR (dynamic range) and in turn achieve louder volumes...I have a monitor volume control for that. ;)
Keep in mind that the music you hear on those albums has already been mastered, and that using further limiting to increase the RMS will indeed lessen the DR, effectively changing the sound of the music.
I guess it all depends on what your end game is...

The goal to these transfers is to enjoy the sound of my old records with almost all the pops and clicks reduced. There is something about vinyl that pleases me, probably since it was the only way of enjoying fidelity when I grew up. The reason why I bring up the volume is so its not so far off other albums or CD's, since I enjoy music with songs being randomized by a media player.
Also, listening to various mastered albums serves as great ear training. I learned that mixing over the years is a craft just as playing my guitar or dealing with industrial machinary.

Sounds like a cool project, and while most of the music we grew up with is available digitally these days, there is "something" about vinyl, something inherent about vinyl that pleases my ears. Perhaps it's nostalgic, or maybe it's that most of that music was recorded and mixed to analog tape...?
I can't even always put my finger on it... vinyl just had its own "mojo". ;)
Have you considered looking into a USB turntable? It may make your transfer process easier... though I can't comment on the quality (or lack thereof) of the motor, stylus, etc.
If you already have a good TT that you like the sound of, then you're probably better off sticking with it - but remember that the quality of the pre/converters you are using to get the vinyl into your DAW will also definitely play a part in the fidelity of the lay-over.

How are the digital levels sitting in your DAW using the phono outs on your TT? Or are you also using an amp in the chain before it enters your computer to bring the signal up to line level?
If it's coming in and sitting around -18dbfs (or so) digitally, you might have a little headroom to work with, to gain up the RMS without using limiting to bring up the level and without altering the sound, as long as the signal isn't peaking in your DAW's meters (single track or master 2 bus).
Understanding though, that there are can certainly be RMS level differences from one album to the next...
I don't know if this is going to bring the levels up enough to compete with commercial releases that were intentionally mastered "hot"...especially during the height of the volume wars... I can't see how you could get the volume on the vinyl versions to "compete" with that newer stuff level wise, without incorporating some fairly heavy limiting... and that will absolutely change the sound of the original vinyl recordings.
Have you thought about perhaps creating a folder in your playback device (iPad, iPod,) where all the vinyl transfers reside, and where you could listen to these, which would give you the ability to turn your playback volume off without something more current jumping in and melting your brain... LOL.. I know you mentioned liking the random play function - but if you did have all your vinyl transfers in one folder, you could listen to those tracks in a way that is more integral to the original intended sound, and not affected by heavy limiting...
I'm just kinda thinking out loud, here.
;)

It's an impossible project to carry out if you want the result of random play of "old" and "new" tracks to have similar loudness. It's quite OK to raise the overall gain of older LP tacks so that they peak at 0dBFS, but that won't make them sound anywhere near as loud as modern tracks where the dynamics may well have been completely squashed.

To re-master the older tracks so that they fitted better in loudness terms with newer ones, you would need the whole raft of dynamic compression gear that modern mastering engineers use (or think they need to use). A DAW plug-in simply does not cut it. In addition, home re-mastering to achieve modern loudness levels would destroy the vibe of older tracks transferred from vinyl LP.

Actually Donny my incoming signal is coming in at -18dbfs on average. Consumer output -10 from NAD phono preamp feeding my SPL Crimson audio interface, lots of headroom.
That preamp does have a USB port, however windows 7 interprets as a mic, so I needed to turn down the gain via USB properties, however, changing records kicks out the USB connection.
Seems to be an issue, maybe static,if I ground the record before playing. Anyway the analogue into line is lower volume, sounds better, no fuss flopping a record onto the platter.

I did lend out my op amp version of -10 to +4 to a service tech sometime ago, wish I had that box, I build analog signal items (vacuum tube guitar amplifiers my specialty 17 yrs)

So since I'm recovering from a surgical procedure, I will build a vacuum tube signal booster from my salvaged parts, what parts I need, go for a drive between rush hour GTA

Yeah Boswell, if I did have a whole raft of analogue compressors, I might match, but the issue with vinyl is the subsonic 8 hz carrier wave that is generated from my turntable and the inherited
surface noise of vinyl. Ridiculous compression would raise that noise floor.

I'm happy with the current results. Basically cleaning up most of the clicks and pops, with studio monitors in my living room is a listening pleasure.

There's nothing around 8Hz inherent in playing a 33 1/3 rpm vinyl record. It could be that your tone arm has a resonance at around that frequency that is excited by clicks and pops in the groove. In order to reduce groove width, the RIAA equalization curve applies 20dB of replay gain at low frequencies (see this site, for example), so a low-level resonance can appear 10 times greater than it orginally generated. It could also be due to bearing rumble, but that is normally a more broadband effect.

Does using a high-pass filter reduce the problem without removing wanted low-end audio?

Yes high pass filtering does remove the rumble. On my trusty old pioneer discrete amplifier the 30 hz filter does its high pass well
to keep the second order resonance 80 hz from happening, small room with JBL loaded cabinets .. deafening ... avoid these days
Interestingly the Yamaha active monitor speakers woofers, don't dance once the volume is moderate that bad coming from the DAW, however,
the Adcom amplifier connecting to my bookshelf speakers do the dance.
I use the stand alone Isotope 6 for tweaking these vinyl waves, the lower band equalizer will do the the high pass well and a brick wall
option is there, unlike the 12 db passive filter found on the Pioneer.

Can I ask...what modern MP3 Method/Service are you using?
Im pretty sure that iTunes implemented a specific LUFS level for acceptance of music submitted to the download service last year ... -16db LUFS comes to mind (?). I'm not sure your vinyl transfers would have to compete as hard anymore... I could be totally wrong about that number, though.
In Europe, the R128 standard sets the LUFS at -23db. I don't know how many broadcast or download services actually adhere to it, though. If anyone here on RO would know, I'm sure it would be Bos ;)
( Boswell )

When converting to MP3 ... I use my trusty Cool Edit pro ...it may be old, but bit rate is usually 256 kb @ 44.1 khz (variable) With cool edit pro
you can batch file a folder, the only caveat, is the wave drawing file extension ends up in the wave folder. Once converted, either Itunes or my trusty
android phone, you drop the folder into the music folder directory.
Itunes the album and album can be tagged, easier to find should that library be large.