Is is better to buy a 912 or a 911 porsche as a project to fix?
 

get a 911, because it sounds like you want to do a half-assed job on the 912. when porsche designed it, they made it so it can handle 90 bhp, no more. if you want to add more power to it, you have to change the tires, the brakes, the suspension Mb Star C4, springs, dampers, drive shaft, cam shaft, exhaust system, aero kit, and the sway bars.

the 911 should be fine,Mb Star Connect C4 but old 911's were pretty bad handlers. porsche put the engine at the back, not knowing that it was a bad idea. rather than moving it closer to the front, they spent 40 years engineering it, and they didn't crack it until the 996. now it's fantastic.

stay away from them, and get a 944 or a 928, although cheap ones are unreliable.