RE: Which firearm would do the job for me?
 

Personally, I'd go with the 7-mag. Depending on where You're going to hunt in Maine, there is a possibility that You'll run into some very nice sized bear up there. Here in PA. I would NEVER go into the woods with a 30-30 for bear, but that is just My opinion formed from past experience. I can justify two cases where a bear was shot in the chest with a 30-30 and got away. Both big bears, and no tracking snow. I've seen some huge bear in PA., and I'm a big fan of blowing through both sides of a bear to get as much blood flowing as possible to ensure a good trail. In the fall, with the bears carrying all that extra fat, a single entrance wound can get sealed up, stopping any blood flow. Bigger is better for bear hunting. JMHO.

RE: Which firearm would do the job for me?
 

7 Mag., 175 gr Nosler, 1.5-5X scope with heavy duplex or German post- type reticle.

Keep yore powder dry!!