Good topic for discussion here. I (as other have already stated) believe your combo will work well for your intent, I would believe (i'm no Bear guru) that the big 30's would be the lower end of the acceptable caliber range. Your WBY definitely has the velocity & the Barnes has the integrity to smash & break any obstacle a Brown bear can throw at it. My only concern would be in the possibility of a charge where a 30 cal might not be favorable anymore. Charges, although not a guarantee seem to happen (at least you hear more about them
The advise to consult your guide is spot on, they are the "been there done that" crowd whose advise should be heeded more than all others. I all actuality, you should be good to go & I will be somewhat surprised if your guide thinks otherwise.
Make sure you author a nice "tell all" for Len to post here, you know us hunting junkies love to read bear stories