Considering on getting a project gun.

I'm giving some serious consideration on getting a project gun to work on when I can't get out and shoot on the weekends.

I'm very mechanically inclined and not afraid to take things apart and put them back together. I'm comfortable replacing, or even building, a new wood stock. Got plenty of hand tools, metric and standard, and some power tools, but no mills or lathes. I know my way around hardware and McMaster-Carr.

I guess I'm looking for more of a restoration or improvement project. Definitely prefer a springer, but open to a CO2. Don't have the gear to do a PCP.
(One day, I'd like to do a bull-pup springer.)

So, does anybody have any advice or recommendations?

I'm not buying yet, so don't send me offers. If I get some good info, I'll put up an ad in the classifieds.