There was a Zora quote on the ZL1 Corvette as told by MCR magazine (in Zora's dialect) "Were six cars made. Two escaped. Four changed inside and sold to employees" I do not know if this is true but there were a few ZL1 Corvette test mules.
The one you mention is most likey the Yellow ZL1 Corvette now owned by Rogers Corvette. He may be interested in the documentation you found.
GM engineer George H. Heberling ordered it then was transferred and it was put up for sale through GM at the zone level. Here is the story.
http://www.rogerscorvette.com/spots/feb98/spot.htm