That's a fine choice. I can tell you that the Leupold fixed power 6x-42mm is a good choice too. I run a Leupold 2.5-8x on my 416 Taylor, but when the stuff gets thick, crawling though tunnels of devils club, I take the scope off completely and use iron sights.

Tim:
I'd opt for a low power variable as well. The scope I have on my .338 is a Leupold Vari X III, 1.5-5. I always keep it on the lowest power when in the thick stuff and it's used for both moose hunting here in the Interior and for elk on Afognak Island. More expensive than many? Yup! But your trip is probably a once in lifetime venture so why take chances on less than top notch gear. Also, as was noted above, I too highly recommend getting open sights put on the rifle as well. Your trip will be quite expensive, why take a chance that nothing will happen to your scope?
As to your your using factory ammo - what's wrong with loading your own with 250 gr. Nosler's? Gotta admit ya have a good bullet there. Just curious as to why you want to use factory fodder rather than your own rolled ammo. Good luck. Bear in Fairbanks