There are a few bullets around in the 525gr that are designed for lever gun lengths. Beartooth bullets makes one and people have been running them up to about 1500fps....
I think Camp Cook here on CGN likes the Jae-Bok Young 550 gr (?) Craters as well. They'll put serious hurt on just about anything you're likely to come across, although as H4831 mentioned, the physics of pushing heavy bullets at top velocities can do unpleasant things to your anatomy. In the US you can get the Belt Mountain Punch Solids which are turned from brass if you feel the need for even more penetration. I read an article in Rifle Magazine a while ago about a fellow that had an 1895 rechambered to 50 Alaskan (?) which he used to take an elephant with those.
But for the rest of us mere mortals, a 350-400 gr. at 1650-1750 fps. probably has more than enough oomph for anything that's likely to get pointed at in anger and won't rearrange your dentures. The Bullet Barn here in B.C. and Ben Hunchak here on CGN ("MT Chambers") have cast bullets that will do the job.
Blufton Bill, if you're looking for Hornady bullets, you might try Dave Friesen ("BC Redneck", 604.316.1910) in Chilliwack, B.C. Like everyone else he has trouble getting components but he might have some.