I would say the bear could comfortably tank SM. The highest level mobs are around the level 40 mark.
That's at least 20 levels you have on most of the trash.

I'd say start out small - pull a few mobs at a time and see how many you can safely handle. You won't be doing full instance pulls at that level. Keep the mobs in front of you and you should be fine.

Are you boosting any toons that can heal you if you need it? If yes then you can probably get a bit more ambitious with the pulling.