You know they made all the special head mods to the later heads right? You don't have to have a special unless you are as crazy as me :banghead:
I bought my first aluminum block and the guy asked me if I wanted the head. I told him no, I have stacks of stock heads and don't need another one. At the time didn't know there was a special head!
I did finally get a special head, a star head, and I have one with a set of big numbers cast in "6 H -21". All these heads have these marks in the same place, right above the 3-4 intake ports.