Unless you’re a resident in AK you’ll have to hire a guide. My guide required 338 Win Mag as a minimum with quality 225gr or greater bonded, monos (Barnes Triple Shocks, etc), or Partitions or A-Frames. If you’re really serious, you might want to book your hunt and then follow your guides recommendations. The size of the bears, terrain, and hunting methods may mean a completely different rifle or ammo from one guide and/area to another.
It’s fun to theorize and hypothesize but until you actually have a destination and hunting method chosen, you won’t know what’s ideal.