David,
In 1980 I bought two E-Type parts cars, a 64OTS & a 68FHC for $800!! The cars and most of the parts are long gone but I still have the engine from the 68 and the head does not have the engine number stamped on it. I still have the commission plate and the car was 1E 35084 with engine # 7E15872. As I know nothing of the history of that car but as it was only 12 years old when I bought it I would think that it was the original head but, on the other hand, wouldn’t use it as proof of anything!