Skeeter 7MM makes a good point.....Black bears are just not that tough to kill with a well-placed shot. I do, however, feel the 30/30 is a bit on the marginal side even though they have killed lots of them. For the terrain and cover you mention, I would recommend the Marlin 1895 in 45/70. Factory ammo in 300 gr. pill. Handloaded, it's a real cannon. And that's where it really shines. Lots more energy than a 30/30. The 35 Whelen is a great choice also.
Whatever you choose, remember the best thing you can do is to place the shot in the boiler room. Regardless of your choice of cartridge.