I would go with a 44 mag, 444 or 45-70.
In Alaska all depends on where you hunt. For example, a .45-70 is handy in you hunt in forested areas where the shots are close, but not necessarily the best for hunting some of the wide open areas of the interior where the shots can be long.
The thing about a .30-06, .300WM, .338WM, or even a .375H&H is that you can take short of long shots as needed. Someone I know uses a .45-70 with iron sights to hunt moose, and is real good at it. But he hunts in areas where 50-yard shots are just about the norm. There are big bears in the areas he hunts, so his rifle choice is a good one.
