Jason (SupernovaSS) has a really nice oil pan on ebay, believed to be an early NOS pan from the 70s.
"This pan is an NOS unit from the 70s that was installed but the engine was never installed or started."
https://www.ebay.com/itm/37363467250...4AAOSwAwRg3gyH
If there is a difference in the 69 Z/28 pan and the 70 Z/28 pan, I would expect they would show on this pan as well.
It looks a lot like the assembly line pan I used in the comparison posted on Team Camaro a few years ago.