I would get a nice mexican block 302. I think they were made in 1970 IIRC.

Then I would build a 331 stroker. Those have a short enough stroke that you won't be smacking stuff around. Plus, they can wrap up quick. All the bang for the buck with less hurt on the block. They should be able to handle up to 15 psi pretty easily also.

And no, I don't have one. Sorry