Are you sure? You may be right. I just looked it up in one of my Chevy books and they just note it as an appearance option which usually means no engine requirement was necessary. The only think I could find on line was at the Corvette forum. They just say it was an option.
http://www.corvetteforum.com/articles/c2/1967-corvette-stingray-overview.php
“...they just note it as an appearance option which usually means no engine requirement was necessary.”
I vaguely remember reading in “Corvette Fever Magazine” that the hood was only available on the 427’s. However, the article mentioned that some small block vehicles were produced with the 427 hoods when the production line ran short of the standard hoods near the end of the 1967 production run.