I See A Couple Of Problems For Bear
One would naturally be the penetration issue for bear.
Deep hard hitting penetration is required for both the skull & body.
The other would be a change in your auto slide cycle rate with an increased power recoil spring....which would also likely require a slightly stronger magazine feed spring to keep up.
Really not a problem if you intend to extensively test that exact pistol setup with enough +P ammo to insure absolute reliability.
My best guess is that you would be only borderline protected with .45ACP+P on any average to good sized POed blackie.
My suggestion would be to switch over to a minimum of a .44 mag (high quality revolver) with a 4" or longer barrel and the hottest, heaviest s.p. ammo that you feel comfortable with and toss a speed~loader into the mix.
With the proper shoulder rig (like a break front vertical) you might be able to use the S&W that you already have.