Chamber size??

my 318 is a 75 model, and i THINK its supposed to have like an 8.4:1 ration, but wouldnt be the least surprised if it were lower. i have stock smog heads with the egr passage and all that crap. i was going to have them rebuilt, but now im thinking i should toss them and get non-smog heads and a no-egr intake manifold. the head volume on mine is supposed to be 60cc too.