Congratulations on getting started. I think we are in the same class. My BP is a bit newer, maybe about 1953. It has the tube support for the head, and the head is 3 phase, IIRC 1/2 Hp motor. I think there was the option for 3 different spindle and Collet systems. Mine has what looks like a #2 morse taper with a threaded top end for a 3/8" N.C. drawbar. I think this system was called Brown and Sharp #2. There is another collete system that has similar taper, but has a long keyway. I don't know what the name of that system is, but a good friend of mine just bought a similar BP with that second collet system. He says I got lucky because replacement colletes for my machine are much cheaper. So far his research shows the price for his collets to be close to $200 each. His 1/2" one is broken, and I think that is the one most often used. When both of us bought our machines, we had no idea about the difference is collets. I have test run my machine, and done some clean-up but haven't made chips with it yet. When I bought my machine (at auction) I thought it would be able to turn a #2 morse taper drill bit, but now do not think I can do that without a drill press chuck having a 1/2" shank driven by the 1/2" collet and using straight shank drills. An informed buyer should be aware of these details (and I was not informed). My friend said there was a 3rd collet option, but I have no idea what that was. The larger newer BPs commonly use an R7 collet system, but I do not think our earlier machines could be fitted with this bigger collet. Maybe someone who really knows these details will teach us newbees the real stuff.
Best wishes as you begin this fascinating journey!!
Paul in MN