911s 1976 casesaver... is it worth it?

hi guys, i am thinking about buying a 1976 911s that needs a casesaver done on it to make the engine run. it has 70k miles on it, needs some interior work and new paint, as well as a few more minor things, and is selling for $3500. is it worth it to buy this and go through with such a project? my dad and i are buying it together, and he was a mechanic for 15 years, so we can do the engine work and prep jobs for the paint, but will we be losing money? anything helps! thanks, Oke