383 build help one piece at a time

A couple comments based on responses...
There's no piston factory or aftermarket that will be close to zero with a factory deck height block. At least none I've ever run accross but I've only built 7-8 over the years. You have to either blueprint the block, which can mean a lot of milling on the decks, or get custom pistons made.
Heads - 516s are nothing near 74ccs. They are typically over 80 when you pull them off and cc them. Advertised compression is for advertising - not any sort of engineering empirical truth...lol. I recommend the larger valves because I always go larger valves when doing a valve job. It allows the seat angle to be placed where I want it and in fresh iron, and I'll challenge anyone to drive one and say "it feels sluggish".
If you want static compression in the 9s, use the KB-400. Have the assembly balanced and the block bored and honed. Have the heads redone. Use the thinnest steel shim head gaskets you can find, and run it. You should be over 9:1 at that point.