Sorry for the confusion. I was only wanting to know about head performance. These heads have been on a 400 sbc and a Dart block so I know all about the cc and clearance issues. I know about the combustion ratio piston and cam selection. Let me ask it this way. With what I am wanting to do, would 20 year old AFR 210's have about the same characteristics as a new set of AFR 195's today. I was trying to leave a lot of the specs out and consecrate only on the heads.