Actually, the 265 Corvette with the 2-4BBL option had a set of high compression heads available, but they didn't have the classic triangle-shaped casting mark associated with the later model powerpack head. I believe it was a single, narrow rectangle above the squared-off pad at both ends of the head. There was another head with two narrow rectangles which was also used on one of the high performance 265's. These heads were very low-production items, and other than for a numbers-matching restoration, there are much better performance choices available.
Jerry
