The heads are good it's just the manifold that's screwed up. I've got another manifold I can use it is very similar and a lot cleaner, but I don't know if it will cause it to breathe differently.

The casting numbers are 3932469 (the bad one) and 3932473 (the good one). the only big difference I can find is the bottom of the good manifold has a block which would push my down pipe about an inch or two down further.

I'll have supporting pictures later tonight.