Sounds good! There are DEFINITELY bear in Maine. I went up to Libby Camps at Oxbow a few years. Great people.
As far as my way of thinking, you should take whatever you want. A rifle will certainly do it's job as long as you do yours. Most everyone up there hunts over bait so the shots aren't long. Also, I assume you've done your homework on where their vitals are located. Definitely different than a deer.
Pictures are a requirement.