A 10GA? umm yeah if you can hit what your aiming at. I'm personnally a rifle man.
Between the 3, I would pick the 45/70 first (with good bullets, not the factory crap), its a toss up between the 338 and the 10GA for 2nd place. if the 338 is set up with a short BBL and iron sights, I would pick it over the shotgun. If it had a scope, I would pick the shotgun first.
Myself, I have my bear guns and my hunt guns. My bear guns I use for hiking and close up hunting. My hunt guns I use for longer range hunting. Mainly I use my bear guns and learn where they shoot at longer distances. I've been charged by a bear while carrying a scoped gun before and never again will I be in that situation.