Anything with the standard belted magnum headsize
That will fit in the action will work with just a barrel change (and psooibly a tiny bit of tweaking of feed rails, but probably not. Going to a .30-06 head size cartridge isn't really practical, as not only the bolt will need to be altered/replaced, but the action rails are already "opened up" for magnum size cases (compared to .30-06 size) and adding & shaping metal so they would work with smaller cases would be cost prohibitive.
Nearly anything in the belted magnum class will work, provided it isn't too long for you action (particularly the magazine). If you want something else, you would be better off getting a different rifle.
I believe .257 Wby will work, but check the case and OAL length to be sure.