It depends on the size of the bears in the area you hunt and the range you intend to shoot it at. Animal size and range. IMO for bear you should consider something in .30 cal and go up from there.
For a really big northern/Canadian black bear, a monster pushing 600 lbs, you need a rifle capable of delivering 2,400 ft-lbs of energy at the range you intend to shoot. For a .30-06 with a 180 gr bullet that range is about 100 yds. A .300 Win Mag or WSM will double that and take you out to 200 yds.
For a more typical 400 lb bear, you need at least 1,700 ft-lbs. A .30-30 will hit that wall at 75 yds. Making it a poor choice, but doable. The same .30-06 above will still exceed 1,700 ft-lbs at 300 yds. Much better.
If you want a lever action to hunt the big black bears your best option will be a Browning BLR. They’re pretty common, new and used. For a more average sized bear, a Marlin XLR in one of the new Marlin cartridges, .308 Marlin or .338 Marlin, would be adequate.
A Marlin in one of the .45 cals would be okay. Keep an eye on the energy at range. They loose velocity pretty fast, due their blunt nosed bullets.
If you’re the nostalgic type, a Winchester 71 in .348 WCF would be a pretty cool bear gun. Or a Winchester Model 1895 in .30-06 would git’r done in style.