I am not sure how to identify an original 'B' nut but is this an original ratchet ring (is there an official name?) on the left beside a reproduction on the right?
Sam, It’s simply referred as as a ratchet in the Parts List. I would agree that the one on the lef is an original (or a very good copy) with, as you note, the lip for the spring which is missing in the one on the right (and on the repro one I have). The hole also looks to be far from circular.
Regarding the B nut (although it’s a screw rather than a nut), the repro one I have has a longer threaded piece as the repro ratchet is thicker.