How much decking is to much?

On passenger car blocks I stop at .060 because the decks ain't real thick. The X blocks can take an easy .125 and IIRC the R blocks can take a bit more than that.

The problem is, once you cut it that far, you ain't getting it back. When cutting cylinder heads I'm even more anal about it.

The decks on the heads are even more thin that the block deck.so I do all my chamber work and finalize size and the cut maybe .030-.040 off and that's it. The more you take off the head the harder it is to get it to hold a head gasket.

If you can buy the correct piston I'd do that. Then you cut the decks to square them up and surface the head to get the chamber volume when you want it.

Personally, I have about a .200 high dome on my piston. I also have the flat of the piston .042 out of the deck. So with a 72 cc chamber I'm at 11.01:1 and with a quick gasket change I can be at 11.25:1 and if that isn't enough, I can still take .060 off the head. That will make me 11.8:1 or so. And I run on cast iron heads and pump gas.