In the "Resto Clinic" column of the March, 2004 Corvette Fever Magazine that I received today there was a question regarding the above-referenced. It seems that one Mr, Steve Selz of Jupiter, FL has a pair of these on his NOM 1965 big block and he was wondering the origin of them. The column's author didn't know their origin, but I may be able to help.
The GM #6272990 casting was used for SERVICE replacement big block rectangular port, open chamber heads. In 1976 it replaced all earlier 69-71 Chevrolet cast iron big block heads of rectangular port, open chamber design. However, these heads were never used on a PRODUCTION engine. They were used on SERVICE engine assemblies for the Mark IV crate "LS-6" and "LS-7" engines available until about 12 years ago. They are still available in SERVICE under GM PART #6260482. Current versions of this part number may carry casting number 6272990 OR 14096188, though. This particular head is available only as a finished, bare cylinder head and is NOT available as a fully assembled head from GM. I think that some aftermarket sources do sell it as a complete, ready-to-bolt-on unit, however.
Steve Selz, if you're out there, that's the answer to your question.
The GM #6272990 casting was used for SERVICE replacement big block rectangular port, open chamber heads. In 1976 it replaced all earlier 69-71 Chevrolet cast iron big block heads of rectangular port, open chamber design. However, these heads were never used on a PRODUCTION engine. They were used on SERVICE engine assemblies for the Mark IV crate "LS-6" and "LS-7" engines available until about 12 years ago. They are still available in SERVICE under GM PART #6260482. Current versions of this part number may carry casting number 6272990 OR 14096188, though. This particular head is available only as a finished, bare cylinder head and is NOT available as a fully assembled head from GM. I think that some aftermarket sources do sell it as a complete, ready-to-bolt-on unit, however.
Steve Selz, if you're out there, that's the answer to your question.