As others said, there are plenty of choices from under 300 to over 500 grains that will work. The single shots can shoot most anything, but the lever action will be happier with a bullet with a short flat nose.
I cast a few different 45 cal. bullets for a single shot 45-70 and 45-90, and a lever action 45-70. I typically shoot heavier bullets (500-540 grains) in the single shots, but those bullets won't cycle in lever actions. I shoot 400-480 grain flat nose bullets in the lever action.
If I were to pick one bullet for all of them (of the molds I currently have), the Lyman 457121PH (475 gr.), Lyman 457193 (405 gr.) or Lyman 457643 (400 gr.) all would work. The 457121PH and 457193 don't have a crimp groove but can be crimped in the top lube groove or over the top of the top driving band for the lever action. The 457643 was designed for lever actions and has a crimp groove. It also has a larger meplat which some feel make it a better hunting bullet.
I also have the RCBS 400 gr. gas check mold which would be a good choice for one to do it all...
