I’m going to replace my truck gun with a .375. I used to roll around with a 45-70, but then I traded it for some gear when things were tight in Alberta, and then used my Ruger scout in 308 for truck gun. After seeing too many monster grizz, and I often work alone, I’m opting for more firepower. Last fall I had a black bear that wouldn’t take off either. He was aggressive and no amount of yelling, loud diesel etc would deter him.
I don’t like the internal mag, I prefer detachable, but it’s not a perfect world.
I thought .375 was a distance large game knockdown round. If you’re looking for closer self protection from grizzly it seems like your original 45-70 rifle would have been a good choice.

I don’t live in Alaska, my stomping grounds are urban, semi-urban, and keep a 870 12 gauge in the trunk. It seems more appropriate for that scenario for many reasons. Top two being it doesn’t carry for a half mile, and if it’s stolen it’s just a couple hundred bucks.
I’m just curious why you would want a Bolt gun vs a Lever gun when MOA is not an issue for a trunk/truck gun.