jpuke,
Having gone the mil-surp to sporter route myself, I agree with a lot of what has been said here about resale value, but if you're building a rifle to use, and don't care about its value to anyone else, go for it. The project can be very expensive (if you go for a custom stockmaker and a high end barrel) or relatively modest (if you go with a drop in stock and stick with the original chambering).
For the first one, I'd stick with the original 8mm. It's a fine cartridge, suitable for almost anything in NA. If you want something more potent, a simple rechambering will get you an 8mm-06, or, even better, one of the "improved" versions.
http://www.ch4d.com/ has dies for the standard version and several shoulder angle "improved" versions for not much more than you'd pay for an RCBS standard set. I recommend the 40 degree version
a la Ackley.
A bit of advice, bring a bore light to the show with you to look very carefully at the rifling of the samples you look at. Be especially vigilant in examining the throat area. This is where heavily used rifles experience serious erosion. If there is a bit of erosion, not too far down the throat, and you really like the rifle, you can rechamber as I mentioned above. That will take out the eroded area. But, it's best to pick one with a good throat.
You'll need to change to a scope clearing bolt handle and drill and tap the receiver. I'm used to the military triggers, but, for not a huge pile of currency you can get an aftermarket trigger with a built-in safety. A drop in stock can go for as little as $75 or so (Ramline), or you can go for a more expensive one. I've been quite satisfied with the Ramlines I've used.
This will give you a basic sporter rifle. You can always make changes/upgrades later.
Have fun with your project.