There are many, many options.
I wont touch on metal finish choices or stock; only cartridge choice.
First off, I'd like to tell you about the only weapon I've had to use against a Black Bear.
I got cornered between the locked passenger door of my truck (truck running, keys in the ignition), a 5 foot deep stream, and an angry mother. You see; I was about 15 feet from her, with her cub forcing himself tightly against her back legs.
Having been charged by this 250 pound bear
twice, a month earlier; I knew I was in a bad spot. It was me or her! I grabbed the closest weapon available, and charged
her. Dumbest mistake of my life... but it seemed like a good idea at the time.
Anywho, it turned out she was, in fact, afraid of big muddy sticks. She ran off into the woods with the cub, and I ran off into the truck to change my underwear.
Big muddy stick +1
8x57 Mauser sitting in the passenger seat... call it a draw.
As a close to my Big Muddy Stick story, I'll tell you where it was.
Florida.
(You, right there! Yea, you, that just sat back and said "They aint got no bears in Florida." You are the reason I added that.
)
Back to the subject-
I think anything from 30-06 up should do just fine. I am a bit of an 8x57 fan, though. I would include it in the group, since the heavier bullets will typically offer equal or better penetration within the proper ranges.
Some specific calibers that come to mind, and may have already been mentioned:
--General use--
.300 Win Mag/.300 Weatherby
.338 Win Mag/.340 Weatherby
.358 Win
.458 Win / Lott (why not)
.35 Whelen/.350 Rem Mag (Know your effective range)
.375 Whelen
.400 Whelen (Don't start the headspace discussion please.)
.411 Hawk
Oh, I just saw your other post about being an 8x57 Mauser fan. If you reload to make the most of the cartridge, or can buy some European manufactured ammo - Go with it! Good shots wont let you down. If you shoot factory ammo - I would take the 30-06, and not worry about buying another rifle.
Reason behind the Mauser compromise:
As I'm sure you may know already; most American made 8x57IS(JS, .323") hunting ammo is not up to par.
Federal is the only company I know for sure that actually uses .323" bullets. Everything else I have measured comes out to .318"-.320", yet are still marked with all the warnings about it being only for the .323" bore.
We pounded a couple brands through a chronograph a few years ago. The only one that broke 2200 fps (23" barrel) was the Federal.
Even with the extra speed on Federal's side, the big brands are ALL reported to be light loads.
They may do the job, but handloads, euro ammo, or the 06 are a better choice.
As for the outfitter - it's your money and your hunt. Do it your way.
-My thoughts.