"the ultimate Alaskan handgun "
As a young teen working on frozen rivers (a DNR job) recall an Eskimo hunter who said, 'don't break wind, a mile away the bear will smell you.'
Well, if you know animal anatomy and you can shoot straight, the 357Mag is likely good enough.
That said, my favorite trail caliber is the 44. Shooting a couple hundred rounds is my idea of a good day at the range, so my choice would be a 44Magnum handgun, with a 3, 4, or 6.5 inch barrel. Before you dismiss the 3" barrel, remember its really a 4" due to the cylinder.
I do not have enough experience with the 454 Casull, but guys that have one are satisfied with it.
For 20 years the sea was my home, always recall the sun going down, and my trusty friend, a 1911 pistol, strapped to my side.