very true man... when i bought my car it had coolent running down the block and 90 psi number 3 cylinder... you could never tell by exhaust, power or anything... i know my head gasket is bad... only really way to know if ur gasket is bad is to tear down your engine... i know it sucks, but i am betting you have a blockage somewhere or not getting coolent flow...
also for cammaro aj... he said he juust replaced his water pump... i doubt it is fucked up.... but is a good guess also a bloockage to the heater core shouldn't affect the fact he is overheating. most heater cores are run in a parallel configuation, meaning the engine is still getting the coolent needed even if the heater core is getting none\
i know my spelling and shit is fucked up but i know i am pretty dead on... da,m beer