Help with 360, too much comp?

If you have an already-compressed gasket you can use clay to get the piston to head clearance. Just check it at three spots: the outside edge, the pin axis, and the inside edge using clay like piston to valve.
You can mill the domes and make them into KB-107s... Or you could have the chambers cut a little bigger. I'm not a fan of losing compression via the gasket but do what you have to do.