[Jack21]

First off, you may not want to ceramic coat the pistons or chambers. Aluminum absorbs heat faster than iron which is why you can go up on CR by as much as a point or so. Ceramic coating pistons and chamber retains heat, and in this case would work against you.

Next, dishing pistons OK, except under the quench or flat area in head. Dish, in this case would be a "D" shape in piston.

Open up chambers a little. Unshroud valves and plug. Tough part is getting all 8 chambers the same.

When grinding valves, seat valves a little deeper in head.

Thick head gasket.

Add these small changes up and dial in your CR.