I have a 350 crate motor (cast # 10066036 'Hecho en Mexico') with facory heads.  Based on my own research I have determined that this is a 8.0:1 CR engine.  I have a set of GM heads ( cast # 3973370) these are 64 cc heads.   The came I am running currently is an advertised duration 278 intake/288 Exhaust 108 LSA cam.  I am looking to swap to a 272/282 (I/E) cam.  I want to know how these smaller CC heads are going to affect  my horsepower.  I know this may seem like a simple question but I am new to the world of muscle cars and performance small blocks. Thanks  

i think with those heads you should have a little increase in compression and horsepower depending the cc of your current heads...low compression kills horsepower but is great for emmisions and fuel economy  at least thats what ive been told