This is what I get.......

Weren't all Pontiac V8 engines back in the 70's based on the same block? I mean, they didn't follow the same big block/small block configuration that Chevy did.
It seems to me I recall reading that they only used one basic block and bored, stroked, or destroked as needed to create their various engine size.
If that is indeed the case, finding a usable "period" engine for it shouldn't be too difficult, or expensive.
A neighbor purchased a 350 out of a junk yard car that he's put well over 100,000 miles on without rebuilding it. We pulled it on a Saturday morning, installed it later that day, and the car's been running fin ever since.
Look around and be a little choosy. There some good stuff available out there, to spite the Cash for Clunker fiasco.