Yes,, we do have some very large (in comparison) black bears in NC. A 500 lb bear is not uncommon,, but also not as often encountered. We have them larger by far,, but in general,, a 300-400 lb black is "normal" in many places.
The bear/caliber/gun debate has raged since man first encountered them.
Pepper spray,, can & is often very effective,, but it too has it's limitations. So do any & all firearms.
AVOIDANCE is the key,, and that's the best thing if at all possible.
But,, if a firearm is to be deployed, then it has to be a type you can handle quickly, capable of reliable follow up shots, have enough stopping power, and the operator has to be efficient in bullet placement.
And gosh forbid,, in the event of an actual attack, allow enough immediate stopping power to prevent as much injury as possible.
The 357, with the ammo mentioned,, can fall into that category,, better than others,, & not as good as some. It's more reliable than a semi-auto in general, capable of quick handling with either hand, and with that ammo, capable of killing a black bear if the bullets are placed in a lethal place. While it may not be a sudden, full bore charge stop in the tracks type,, it can do the job. (Not much can do that kind of sudden stop anyway.)
COMBINED with pepper spray,, it's a good combo to carry for peace of mind in my opinion.