Bob
I think your assessment is probably 100% correct. Hard to guess how production had been compromised in that period. Case looks too good to be aftermarket. Thanks for sharing the pictures; fun to study and speculate.
A couple things I'm curious about.
Is there case in the pits on the underside of the receiver?
Do the serial numbers look relatively similar as far as the font style?
Have you had it lettered?
Thanks again for sharing and I apologize if I seemed excessively critical.