I think it is early 1950's. Mine is a 1953 and is almost identical to yours. Yes, a good bike shop can add threads to your fork. The problem with doing so is that then the upper truss rods will be too long and will need to be cut and threaded also. That part can be a pain in the butt. If you determine you still need cups, etc., I have a nos Wald replacement set that I believe is correct for your frame. Also after measuring a comparable frame here, should you choose to replace the fork, the steering tube should measure 6 1/2 inches from the top of the lower race to the top of the threads.
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