There are custom ammo makers in the States who make higher than RP and WW level ballistics. This higher pressure ammo is suitable for the newer lever guns, but is still not loaded to the nuts for them, or for the Rugers, Brownings or Mausers.

The .45/70 is easily loaded on hand tools, especially for a single shot. A 'simple' Lee Loader is all that is really necessary - along with a good loading manual. Powder scales are never a waste of money.