Although I guess the bears could still be a problem I would still take the gun I am most comfortble with. That's a long way to go and I would want to tke the gun I shoot the best and a .270 is definately a good one for deer.
Please be sure to give us a full report after your hunt as I am very interested in this one. The hunt itself, the boat you used and what he charges under normal circumstances, any other charges you ran into that are not normal or were unexpected.
Good luck on your hunt and waiting for the report.