Lend me your experience

First off any time you open an engine you better have a couple grand laying around, all the little stuff adds up. The 76 heads are smog heads, good heads in my opinion just have to plug the holes above the exhaust ports and do some porting. There’s a lot of meat In The bowls that can go but the ports them selves are pretty good sized just a gasket match on that side and shave them down a bit and you should see quite difference. Thats my experience with the 596 head anyway. But as long as you have it apart I would go ahead and get a rebuild kit right away.