IMO the thicker the gasket, the more likely it is to fail. That's not to say it will happen though.

how thick are the piston crown's? is it possible to have some material machined off to give them a dish?

Basically, the higher the comp the more limited you are to how much boost you can run before you have to retard the ignition sevearly, closer to detonation, more heat generated. Unless you have a high octane fuel (higher than V power!!).

Put it this way, a standard RS Turbo is 8.2:1.