[WSSix]

If you can afford to have the car taken apart for a little bit, it might be worth the effort to first take a head off and cc the combustion chamber. That way you know for certain your current compression ratio and can select a new cylinder head accordingly. Of course, you can always go with a larger cc head and simply angle mill it before putting it on the car. Too big of a combustion chamber and you'll lose performance. Too small and you damage the engine.