Agreed, and that is the question. Where is a safe stock block limit? Also, where is the race blocks limit?
I can’t answer these questions. There is just not enough information out there. Who’s done it? Who’s still doing it? Who is planning for it?
The OP asked about combinations. That’s it really. Everyone’s concern with the block is a good concern considering the parts he is asking about. Those Indy heads can potentially make some serious steam. He hasn’t a plan on them, just questions on combinations.