I have a 90 350 shortblock that is a rebuild from Advance Auto Parts. It has inverted dome -23cc pistons. The heads that are on it are a set of 76cc heads from a 73 truck motor. I'm running stock felpro head gaskets. I was wondering if I should get some heads with smaller combustion chambers. I was thinking of running some 305 heads because I really don't turn the motor over 5000 rpm. I heard these heads are 58cc but they don't really flow very well over 5000. What are your thoughts?