Seiko 6139-6007 - Value?

I picked up a Seiko “Blue Pogue” that was mislabeled as a 6139-6005. Was in fact a 6007. All I know is that it was only produced for around 3 months between Nov. 1970 and Jan 1971. The caseback was on so tight I had to super glue a bolt to it to get it off with a wrench. But man o man, the insides were almost untouched. There wasn’t the usual evidence of servicing. And the dial is almost immaculate.

But the case has the usual wear.

Does anyone know anything more about this variant? I can’t find many sales records online. In fact, I had to make a whole new category for it on eBay and Chrono just to try to sell it, because the reference wouldn’t even show up.

What’s up with this one? What’s the story? Is it rare or just an irrelevant variant?