Be very careful... there are a lot of fakes, including the parts sold by Gibson for $$$$
I'm not sure how you'd go about verifying the authenticity of an actual vintage BB other than dealing only with known persons.
Try reaching out to James at ReWind Electric. He may have some in stock. I got mine from him, although they were part of a harness restoration. You can rest assured that if he does have some and he is willing to part with them, that they are in fact the genuine article.