I use a scoped bolt action when hunting bears, but I always take my open sighted Rem 870 with slugs on my trips as well. It is a lot easier to handle in the thick stuff after the shooting has stopped. I believe a lever action 45/70 with open sights would work as well, so use what you are most comfortable with. For me, it is the 870. In open country, the shotgun would be redundant IMO.

Here's a quote from "Bear Hunting in Alaska" by Tony Russ, pp 272-273: "If you do have to shoot a bear at close range, be prepared. As Keith Johnson, a notable brown bear guide, says, "...any pistol is a poor weapon against a brown bear." (Unpredictable Giants). Stopping an attacking brown bear at close range with the most powerful handguns made is difficult even in the most expert hands. Twelve-guage shot guns may be slightly better weapons for this purpose, but their soft slugs don't penetrate as well as dangerous-game bullets from a heavy calibre rifle. Bear hunters should be carrying a heavy calibre rifle with a well contructed bullet anyway, and that is what you would want to use to stop an attacking brown bear"