67 Z28 intake with '65 casting date

[L72copocamaro]

For arguments sake, let's say you're right. Then it proved inadequate and may have led to another 0 design that led to the tuned runner open plenum 610 manifold. There were thousands of experimental parts made back then to keep GM competitive. Your manifold could have been cast for any number of reasons or applications. It's a very cool piece of Chevy history, but saying it has to be a Z-28 prototype is probably not accurate. It is dated way before the conception of the Z, and VP stated that the engineers used off the shelf parts for the prototype Z. So the manifold was apparently not specific for the 302. But who knows, you could just as easily be right, but I doubt you'll ever be able to prove that.