meh, I disagree the later head is better for performance. It's the same cc chamber, the same valve sizes and essentially the same port configuration. "Revised" is the term Chrysler used. I "guess" if you really get technical about flame propagation and all that nonsense, the revised head might be better, but you'd never feel the difference.Nope. There was a change around 67/68 that I remember, was always told to use 68 up head for better performance, which includes both drool tube and peanut head.
It's in the articles section at the /6 site as well as in Dutra's book.... Not much difference in any of them. I think the drool tube heads are lighter, so there's that.. clean up the porting and it matters less.