Would this be a deal breaker?

Dartnut said
Have a very good look at the frame rails and the torsion bar cross member.
If those have holes in them or are just recently undercoated, you probably have a $5,500 parts car. Did you actually determine yourself that the engine and trans are original to that car? Or are you just taking the guy's word for it?
If it's worth it to fix it up is only something you can decide.
Restorations aren't cheap even if you do the majority of the work yourself.
And they are very time and space consuming.
How about more pictures?

Good points, especially about the structural components...THAT would be a dealbreaker, IMO.

If you can climb under there with a flash light, look for the markings in the casting on the side of the block. It will say if it's a 318, 340,360 and the manufacture year.. Who knows, it could be the original 340.