Theoretical cam question

If you're just wanting some more compression, why not just spend the money on the heads? I'm no expert on the older small blocks (myself and all my friends run magnums) but I'd look into seeing how much the heads can be milled before spending money on swapping pistons. With a good mill and thin head gaskets you can get a decent bump. I don't know how much compression your trying to gain but anything over 10:1 the benefits of more compression start decreasing.

It's something to look into at least before dropping a bunch of cash on the short block. I'd also be in favor of going to the larger valves with some minor bowl cleanup work.