How far in the hole 318 pistons

Dale Davies said
By 72 emissions were kicking in and the CRs dropped into the outhouse basement. Between either dish pistons or 0.040" to 0.100" down and combined with open chamber heads the combustion was terrible and prone to detonation. Best bet would be figure new pistons to zero deck it with modern rings with 1.2mm width. This reduces friction. You want pistons with 2 valve reliefs not 4 and flat top. Also plan on in the future getting heads like the Edelbrock closed chamber for good quench which is high mixture motion. Good for efficient combustion.
Calculate your compression based on that and order a cam, lifters and pushrods to match. You can change the pistons next winter and then the heads the year after that.

Well, sorta. While it is true that compression dropped, it's also true that horse power ratings changed from gross to net. So that makes it appear that engines lost a ton of power from 72 onward, when in fact, they did not. That'a always a part of the equation people sometimes forget. With all else aqual, a 10:1 engine for example, will make only about 6% more power than an 8:1 engine. Compression alone isn't the end all be all a lot of people think it is.