I can't see why a 45 Colt wouldn't be enough gun for either. Deer (whitetail) are simply not that hard to kill. As for bear, I cannot say, I've never hunted one. I have hunted feral hogs quite extensivley , and can't see how a large boar wouldn't be comparable.
I used a Chiappa arms 45 Colt (92 Winchester copy) for several years hunting hogs, and found the factory stuff to be lack, when I began handloading, and using Hornady Interlock 350gr, I had me a regular hog-hammer. The thing is, though, with handloading for a levergun, I wouldn't take it quite as far as the single-shot pistol (contender) loads. At least I never did, and I didn't need to either. With the 45 Colt, pistol loads and rifle loads are a whole different thing, and most of the box ammo out there is pistol stuff. If you handload for it, you will see this caliber's true potential.