"Maybe it was a change as they were built ??? but the pictures I have show 4 hood pins and complete removal of the hood in the pits and placed on the roof of the cars."
IMO, this does
not sound like a factory setup. At least not for Super/Stock. Maybe A/FX? If I were a betting man (and I am), I'd bet that it was a racer modification.
Personally, I've never seen any pix of those cars with a quick release (i.e. hood pins) system installed allowing quick hood removal.
Here are some early pix of those cars at Beeline Dragway in 1964:
http://arizonaracinghistory.com/64winternats.htm
Granted, most if not all of those cars pictured there are Max Wedge cars since (I'm pretty sure) the 426 HEMI was released in April of 1964.*
M68
* Or was it February?
** Yeah, it was February 1964 because Richard Petty won the Daytona 500 with a Hemi under the hood as well as the 2nd and 3rd place finishers.