High-performance 265's and some 283's from the middle to late 1950's used a head with a rectangular pad on both ends of the head, and two small rectangular projections on top. They were manily used on Corvettes. I believe they had slightly smaller combustion chambers than the standard V-8 heads. The "power pack" heads on the 4-barrel 283's had a rectangle on the end of the head, with a triangle centered on top of it. Those heads had 58CC combustion chambers.

Try this link:
http://www.fastnuf.com/Headguide.html
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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