Maybe they changed the engine as well. These guys can run the engine numbers for you as well and tell you if it is stock.
I have an '81 L82 for sale right now. They were produced but are rare.Well, my facts came from the 1953-2003 Corvette history poster hanging at the carlot. Your info is probably more correct. The poster does mention the dual build sites so I guess it got something right.
It's got a lot of specs for each motor I mentioned. I wonder where they got them if it dosent exist.