Gently...
:-)
M2c...
By the time you have a working Neve 1073, SSL or API class pre amp, you have gray hair and it has cost you almost as much as the original box*. The quality and design of those kind of pres go down to the choice of 1st class components some of which can't be bought in a shop and can't be simply replaced with an equivalent. Even shape and material of the casings (inside) have been carefully designed to optain the best possible performance. If you actually find a construction plan and layout/schematics for a really good pre amp you still don't know if its sound characteristic is what you are after and there will be no warranty, either. There are kits out there for good standart pre amps, but then, those don't cost that much ready build in the shop. I think, you have more fun and safer working with a bought one, even if it takes safing up money.
How can I say that? I am into electronics for 34 years, now, and tried a lot. Most DIY-boxes got replaced, as soon as it was possible and some of them were a pita from the start.

Big K

* if you do payed work for as long as it had taken to build this pre, you should earn a fair chunk of a little Neve, already.... ;-)

Huh...big K is right in some respects, many of components are hard to come by these days. Any substitutions will have trade offs....however if you really know what your after, there is no reason why you could not get it. As for simple kits to start of with there are several options:
[="http://www.seventhcircleaudio.com/"]DIY Mic Preamp Kits - Seventh Circle Audio[/]="http://www.seventhc…"]DIY Mic Preamp Kits - Seventh Circle Audio[/]
[[url=http://="http://www.jlmaudio…"]JLM 1272 Switch Kit[/]="http://www.jlmaudio…"]JLM 1272 Switch Kit[/]

However as Big K warned this is an art, you really need to know what you want circuit wise before you start, otherwise you could get lost in the maze.

Best of Luck.

I have not yet worked with those. From the price region they are in they should be good.
In that range you get something like an UNIVERSAL AUDIO 710 TWIN-FINITY or a FOCUSRITE ISA ONE DIGITAL, which are really nice pres. The 710 has even tube & solid state stages...
But the SCAs might be a good choice for learning about the job...
Maybe a bit too expensive for a soldering training.. ;-)

I tell you, even I would do some practicing, if I had to work on a difficult soldering job after a long time.
Lol,.. the last time we changed 120 double axis potentiometer on an analog console. The circuit boards were all multilayered and had to be soldered through. A fiddly task.. :-(

Maybe you go to the next radio shack and buy a cheap assembly kit (fun or useful) with 50+ components. If you get serious try the SCA's DI-box. Not too expensive and always useful to have...
If you finish that and it is functioning, too, you can make the next step to the 400 $ pres...
I'd love to hear about your progress and wish you a lucky hand.
A little advice: keep a multimeter handy and check each and every component befor you use it on the board. In an intermediate examination at my politechnic university (1981) I almost flunked the practical test due to a defective Zener Diode in the provided components kit of the digital controller board I had to build. .. It would be rather annoying for you to see your circuitry going off in smoke, too.
;-)

Smoke is part of the game, the trick is to keep it inside the parts ;)

They work better with the smoke inside.

Kits...
There are tones of simple kits out there.
Try [[url=http://[/URL]="http://www.canakit…"]Electronic Kits[/]="http://www.canakit…"]Electronic Kits[/] for other simple kits to play with

Tools?
What kind of iron do you have?

You can solder with any iron, but a good one saves you time and grief.

I would get a temperature regulated one...

Technique...
Check out my soldering guide for a quick refresher....
steller-studios.com/PDF/PCB Soldering Method R0.pdf

.