Re: Late 70's JB label
Funk, I think you're over-analyzing the camera distortions/angle...
John, I have an original late-'70s JB ("The JB Model") here that I can compare with the one you posted above...
The brass screws appear to be correct, as is the finish on the base plate. Interestingly enough, the stamping markings on the mounting tabs are identical on mine (in other words, the tooling marks where the tabs were bent).
Furthermore, the bobbins on mine also have the square holes like that one.
The label size and placement is also spot on to my "The JB Model" pickup's own label. However, I have seen the top layer of these early labels separate. It's possible that this happened and someone hand wrote the model name in its place. Might be worth reaching out to Seymour to see if he ever marked pickups like that (I've never seen it, though).
Assuming the DC resistance matches up, it appears to be a legitimate first-gen JB to me.