Bob,
My first impression tells me it's good, however, the flawless condition of the reverse post & claw assembly gives me reason for pause ... I'd say a real buckle collector would have to see that to make a better judgement call for you.
Many of these buckles were private purchase pieces, for EM's too, so there are many styles of these Bavarian Koppelschlösser to be found. Could this be one that was tucked away in someone's sock-drawer? absolutely.
I would definitely ask for more feedback from experienced buckle specialists as this might turn out to have a happy ending for you ... I hope it does.
Best!
Bill