as to Mike P's response I thot that my decision to go with vortecs rendered all ref to cast irons moot. given that, I appreciate rumrum's info on 906's n 062's. that's what I needed to start looking in the right direction. of course I am grateful for all the excellent info rendered by all rspondents. I mention again that ime not looking for a super hi perf engine, just a pump gas runner with compression that precludes detonation burning such.