I used to live/work at a hatchery in Southeast. Had nearly daily close-quarters interactions with brown bears. Pretty cool critters, when seen from a safe distance. Pretty intimidating up close.
I once saw a teenage brownie stick it's nose on an electric fence, behind which was some very very attractive fish food and smelly stuff. The bear yowled and lit outta there like, well, it hit an electric field.
I'd suggest you pack whatever gun you feel most comfortable shooting. They are incredibly fast animals; if you need to shoot one, you may not have much time and you may be flustered. Debating the performance, penetration, and energy transfer of different calibers and loads is great, but irrelevant if you can't put the bullet where it needs to go under a lot of pressure.
Hope you don't have to use whatever gun you take. Be loud and keep a clean camp. I never encountered a bear that wouldn't leave if given advanced warning and an escape route. Seems like most problems involve bears with food or bears getting surprised.