I have a 1975 chev 350 out of a truck. I was told the stock pistons have a 13cc dish in the top of the piston, I assume this was to lower compression for the smog motors. I have replaced these pistons with flat top units that have valve reliefs cut into the tops. The crank and rods were left stock. The stock heads with 76cc chambers were replaced with Edelbrock RPM Performer aluminum 64cc heads. The cam I used was the GM RV cam. I have two questions...what would my compression ratio be and how much more cam lift could I safely add with roller rockers that have a 1.6 ratio? Anyone know the cam specs for the RV cam? Okay I said two questions but I guess I asked three. Thanks for your help.