The bush across this country is not simply a willow choked jungle without any breaks. The land is dotted by lakes, which provide the opportunity to spot game at long range along shorelines. Power lines crisscross the landscape, and game animals make use of these so that they can move more easily, so they can graze on grass, and so they can more easily see approaching danger. You don't have to travel very far in the bush before you run into open stretches of muskeg, taiga, or tundra. In some areas, eskers or rock outcrops provide the viewer with wide open vistas. In other areas, fires or commercial cutting opens wide stretches of land.
The point is that the bush hunter is better served with a rifle than a shotgun, and for the record, that rifle is best if it can reach out to a quarter mile. But because the hunter can find himself in a situation where the action might be close and fast, a rifle that handles easily and quickly has the advantage. A short barrel alone isn't the full answer. For the rifle to handle well, it must have balance. If the barrel is too short, with too light a contour, it will feel clubby, and prove to be slow and difficult to hold on target unsupported. A short barrel must have a heavier contour if it is to balance as well as a light contour long barrel, so just whacking that 24" tube off at 16" might not produce the desirable results you envisioned.
A scope should be low power, with a wide field of view. Magnification makes it easier to see a distant target, but is a disadvantage for close work. A low power variable would seem to provide the best answer, but its not the only answer. I have done some credible shooting on game sized targets beyond 300 yards with a 2.5X scope; after all, the primary benefit the scope has over irons is not it's magnification, but the fact that it puts the target and the aiming point on the same focal plane.
I was brought up on bolt actions, so the bolt gun for me will always be the top choice. But there are all sorts of actions that are suitable for the bush hunter, from bolt to lever, to pump, to auto-loader, there is no one right answer. But IMHO, you severely limit yourself by choosing a rifle/cartridge combination that's only effective to 150 yards, just because you hunt in bush country.