Compression ratio and cylinder heads?

[FMG CAMARO]

I have a 1968 camaro with a small block chevy. The engine is bored 60 over. It has flat top pistons and GM 76 cc heads. The car made 267 rwhp and 307 torgue on a winjet dyno. I purchased an engine package from PAW about 12 years ago. Those are the specs I remember. The cam has a .488 lift. I do not know the other cam specs. I would like to upgrade to aftermarkert aluminum cylinder heads and a bigger cam. How much will a smaller combustion chamber raise compression? ie. 64 cc heads vs 76 cc heads. I also read an article on compression and it stated that just because the pistons are suppose to be 10:1 with 76 cc heads doesnt mean it is. Basically there are other variables to determine true compression. Also if I take off a cylinder head is there a way to accurately determine compression with specified combustion chamber? If anyone can explain all of this to me I would appreciate it . Thanks.

[FMG CAMARO]

Just saw copo rat's thread. Pretty much answered my main question. Thanks.