The pistons that are in it are definetly not flat. I have a GM part number of 3968875 and the pop up portion just about fills the combustion chamber. Anyone jnow where I can look up that number? Also it has the stock bore of a 402. I think it's 4.125 and it came with the nodular iron crank. I bought it from a guy for 500 bucks. I think I got a dam good deal! What compression ratio would that give me?

Thanks for the input guys.