.300 win mag for everything.
Farthest rifle elk shot, 225 yards. I've not shot a moose or caribou. But when I'm hunting the woods, you can practically walk up to a moose. Would be a rediculously close shot.
The caribou hunts I see on TV look very similar to antelope hunting as far as the spot and stalk and inability to get close. Longest antelope shot was 385 yards.

The one thing I recomend to hunters coming out here is to know their balistics, and practice short, medium and long ranges. Know what your bullet is going to do at a variety of ranges. Use a good range finder. And squeeze.