A properly placed shot into a bear's anatomy will kill with either cartridge/load, you've mentioned.
BUT....personally, they may not 'stop' the bear...then again they might?
Killing and stopping are not always the same thing...shot placement will be the major factor.
A guy I knew at King Salmon, Alaska (back in 89), shot a 17 yr old coastal brown bear at 90 yards with his .460 Weatherby (yes he can handle/use it, along with his other BIG Weatherbys), he hit the sow with a 500 gr Hornady, behind the shoulder/through the lungs. Down went the sow...up went the sow immediately, and came for him/his partner. The poor camera guy merely tossed the camera and RAN! AFTERWARDS, it made for a humorous video. but not at the time! His partner's shot from a .458 Win (350 gr Hornady) hit the front of the sow (found out later it stopped under the hide on her rump), and a second shot from the .460 W hit/broke the left front shoulder and down she went, not dead, but down due to a broken shoulder. The sow expired 15 minute later. It took another 30 minutes for the three guys to regain their composure - can't say as I blame them!
That sow was by all rights dead from the behind the shoulder lung shot, she just didn't know it is all, but it didn't 'stop' her!
I asked the guy why he hadn't shot to break the front shoulder with his first shot...he meekly said he knew better now!
A friend up in Arctic Village, Alaska (200 miles north of Fairbanks) shot an interior grizzly as it ran away from raiding his fish cache (passing from left to right in front of him at full run), with his 6.5x54mm Mannilcher-Schoenauer carbine. Using a 160 gr bullet around 2100 fps from that 18" barrel carbine. The first shot hit behind the right side ribs, angling to break the left rear leg, down went the bear. Two more quick shots ended the bears life. The first shot placed from that lil' 6.5mm round stopped the bear, it just didn't kill it until 2 more shots were fired.
The author, Charles Sheldon, in his book, "The Wilderness of Denali" (an excellent read I'd highly recommend for you, considering where you are planning to hunt, interior Alaska?)(search for it in
www.abebooks.com), from 1906-1909, collected moose, sheep (he helped classify sheep in North America), grizzlies, caribou, etc., for the Smithsonian, and other museums. His collecting took place between Fairbanks and Denali Park. It is estimated that in his long career (collecting in Canada and other places besides Alaska), that he harvested between 70 and 80 grizzlies! Times were different back then, ok.
What did such a collector of large game use as his primary cartridge/rifle for all of those years? A sporterized Mannlicher-Schoenauer in 6.5x53R (a rimmed version of the 6.5x54mm M-S). Not many folks would even consider that power level of a cartridge for such hunting today...but it did its job in yeoman fashion when called upon. How many grizzlies have been taken using the .30 WCF, in the past 100 years?
The old adage of, "It's not what you shoot 'em with, but where you hit em, that counts.", is of a major concern in this scenario.
"aim small, miss small..."
One thing about 'interior' grizzlies, they are not the much larger size bears one thinks of most of the time for Alaska, the large coastal fish eating bears. Interior grizzlies are predominantly smaller and sprinters, not having the fish protein that coastal bears get, which grows them so large.
Again, I'd suppose my opinion is probably worth the $.02 of others, but either should do ok. You will have other hunting partners with you as well, correct? So there may be strength in firepower from your friends? Well, hopefully anyway...lol
If you are on a guided hunt, then your guide should also have a 'suitable' cartridge/rifle combination to handle such an encounter?
Now the interior has plenty of black bears, and these lads can get quite large themselves. Either of the two calibers/loads should work fine if you'd have a need to entertain one them!
Of the two calibers/bullet weights you mention, which of the two rifles shooting these, do you like better/are more familiar with/shoot better? Sometimes we shoot better, what we like better? There is something to be said in using what we feel comfortable with.
Hope this lends some insight...
(I've wayyy too much computer time during the winter like this! LOL)