I have use 5C's (64th set) for everything in my big lathe. In my small precision lathe I use 3C's (again 64th's) since it's headstock AND tailstock are bored and made for 3C.
If you have a Buck-style 5C chuck coming, that is all you need. Zeroing it in to low run-out will be fun but can be done with a little patience. I took hardened reversible top jaw 6" 4 jaw and 8" standard 3 jaw (both scroll chucks) units and modified them for "zero-set" so now I get better tolerances with them than my 5C chuck! Can you say 0.0002 runout on a 3 or 4 jawed chuck? Really nice. But 5C's are still used a lot for various thing in the lathes and mills.
I also have the main sizes of square and hex 3C's as I work with that bar stock a lot in the work I do.
Good find on the lathe. As I have always said about REAL lathes, they come in two sizes: good old big uns and big old good uns!
bangerjim