Having owned a 30-06 for 2 years and hunting anything from roos, pigs and water buffalo, I'd say that that would be a bare minimum for where you're headed and what you're doing with it (feeding the family).
180 grain 30-06 winchester cxp, even when placed right will take a couple of shots to bring down a 800-1000lbs buff just because of the size and pure anger of being shot the first time!
As mentioned before reliability of your weapon may be the ultimate factor, not the usability of the modern round in your conversion, in deciding whether to keep it or perhaps get a trade on something.
Have a blast up there! One day I'll get up there to see the wilds of Alaska!