a metal head gasket, no matter how thin it is, can only raise your compression but so much. i mean, it'll raise it ever so slightly, but milling the head would give it a bit more, but not if you only do .010". if you go too far, you may not clear pistons. you could also deck the block, but here again, you may have clearance probs. better to do the head gasket for security sake and then do higher compression pistons.
higher compression valves?!?!?!