JD-Zincavage-
Two powders with which to start reloading your .25 Roberts? IMR-4064 made the original users of the .25 Roberts happy in the early 1930s and 80 years later, current loading manuals show it still to be still very useful in the standard .257. Alternatives to 4064 are Alliant RL-15 or Accurate 4064. Another useful starting powder would be H4350. If it should be unavailable, IMR-4350 or Accurate 4350 would be OK too.
It's evident and commendable that you're doing pretty thorough homework in preparation for shooting your piece of history.
--Bob
