Cannot find info reflecting a B prefix on this site:
Gibson Electric Guitar anbd Bass Serial Number Date Code Information
Check following link for pics and description by model year.
Vintage Guitars Info Gibson flattop vintage guitar collecting

I’m happy to help further over the phone at https://www.6ya.com/expert/donald_f2ed37026a3ac881

I am certain that Gibson has a web page in which they list serial numbers of all of their guitars going way back. Google "Gibson guitar serial numbers and year manufactured" or something like that, and you'll find it, or take it to a reputable music store with a large guitar section and they can consult their Bible of guitar info and find it for you. Buy a set of strings or something and they'll do it. But you can probably find it yourself. . .