Sounds like a 1-4 power variable would fit your needs. With todays saboted slugs, a rifled barrel slug gun should give you rifle-like accuracy at 60 yd, assuming you do your part. And, if you hit a bear in the vitals with that slug, it'll put his lights out right now.
However if you gut-shoot him, it won't matter what you use to do it.
But, frankly, I think, if you are talking about black bears, your imagination is your worst problem. We hunt around them all the time. They want absolutely nothing to do with you.