On the clipping question, your ears should be the best guide. But if you say he is clipping a lot you should probably rerecord. (If he's an old fart like me and recorded on tape back in the day, he's probably obsessed with keeping the signal pretty saturated. Not used to the headroom of 24 digital bits.)

As far as the general approach to acoustic guitar, a little compression or limiting is very common. But the typical treatment doesn't adjust much more than (probably) the peaks that he clipped off. Set the threshold to push down the peaks a bit and leave the softer dynamics untouched. A little reverb to add space. Tweak the eq. Good to go.

Now there is another approach that uses strummed acoustic guitars as a pad, heavily compressing them, usually through multiple stages of compression. CSNY (and other groups in the era) did this sometimes in songs that had a lot of other things going on. The trick here is to create a nice smooth consistent strum that still sounds like an acoustic guitar. It's used as a background element so it isn't intended to be you favorite acoustic guitar sound when soloed.

Good luck.

You know Bob - it's presumptious to assume that a "young fella" like this (assumption inserted here) knows what CSNY is. He might assume it's "Crime Scene New York" the new drama on whatever channel that shows that stuff...

Don't hit Google just yet -
Crosby, Stills, Nash and Young

Sorry...nothing but sarcasm to contribute to this one...

Cheers -
Jeremy
(Young at heart, old at soul)

Young at heart.
Youuuunnnngg at heart.
You're so younnnngggggg at heart.

The Bluebells?

Are you really sure your dads stuff is actually clipped? Meters banging in playback? Or is it just hot when you try to mix it? I too have a tendency to pack a hot signal in digital recording. But not to the point of flat topping heavily. A little creative clipping can at times be advantageous. I'll do that sometimes to introduce some heavy 3rd harmonic content on mostly percussive material. A very little bit on acoustic guitar can also be successfully utilized. But you don't want to leave those kinds of signals intact at that level. They of course, need to come down a little in the mix. This will still retain its flattop transients which will introduce a harder sounding attack on whatever that happens upon. But too much of that makes for some serious fatigue for your listeners. In that respect, if a redo isn't possible? I'd suggest you attempt some clipped peak restoration, if your software supports such features? But if the clipping is excessive, not much can be done. Reverb & bandwidth reduction can help to mask some of the distortion. Bandwidth limiting such as 100-10,000 hertz can actually cleanup otherwise ragged sounding overload on some instruments/tracks. These are all compromises in pursuit of make do restoration. That's not to say you're recordings are screwed. But it will take some fancy work to make them sound pleasing.

Let me know how things go? Let me have a listen and I'll see if I can help?

Thanks for your kind words and your anticipations.
Ms. Remy Ann David