[Big-Foot]

Roy - The aluminum head will dissapate heat quicker than will the iron head. It will also let you get away with a little more compression on today's pump gas - although Ron Widener here has found out, you really can't get away with a lot. With aluminum heads we typically will set the maximum pump gas compression at 10.5:1 for a "Sunday Competition" engine, and then 10:1 on cars that will rarely see the track.
Your engine would really like a set of AFR185 heads. The ports are not so huge that you loose the all important velocity for docile street driving.