As for egregious confusion, I posted a link in my second post showing how the lens would have been marked were it an echte Dagor. I later posted several links to lenses listed on feepay, showing the various markings of various vintage lenses.
I also recommended testing the lens, and gave that reason - spacing.
As for the shutter, Compurs weren't too easy to get for a while after WWII. B&J could well have used a NOS or used prewar shutter. Or someone could have taken the cells from a shutter B&J mounted it in and put it in this one. B&J remounts are best approached with suspicion and a good return policy from the seller - but I know of one, a 270/7.7 (which maximum aperture means the glass dates from the 1890s) that is every bit a Dagor in performance - and I've heard of others. The OP could have a dandy little lens there, only one way to tell.
I've been owning and using Dagors for quite a while, and I've learned everything I can about them. You may want to google my screen name... ;)