For an age clue, I would search around for other model B's with that fork crown, there appear to be a few used for them over time. This one is one of the less graceful ones, but I think original, the bike appears to look and sit correct from the side view. I'm less sure about the paint, I would expect some evidence of the original graphics, somewhere.

Love the steel bar and stem, bike has definitely been updated through the decades.
Actually surprised the cranks were not updated due the the minimal difference between the two rings.