Tom, that was the size of the engine destined for the Trans Am series but the development was too late and slow for the Pontiac guys who wanted to compete. That's why they started the myth.

Nash, it's an insidious right-wing plot! Even Pontiac people that should know better have been sucked into this myth, to the point of listing it as FACT!

http://www.pontiacpower.net/fact.html

Scroll down in the "Facts" to the late '60s and you'll find the myth.