Came here to say something similar to this. All weather with a short barrel, 26.1" overall length. 44 Mag would be nice, but I'd die for one in .454 Casull that could also fire .410 shotshells and .45 Long Colt. You could do it - Taurus makes the
Raging Judge Magnum that accepts all three cartridges, and a short barrel lever action carbine would be a perfect match for it. A 14" barrel should permit 4x or maybe 5x shells of .410, and 6x or maybe 7x .454 Casull rounds.
You could really cut into the
Chiappa Alaskan market if you wanted to take a bite of that apple - they're like $1800 Canadian, while I've seen your all-weathers out there for $1200. The Alaskans are expensive for what you get, and a cheaper alternative that could fire a variety of ammo (.45 long colt, .454 Casull and .410 shotgun shells) that's still Non-Restricted could really be attractive.
Even better yet if you load the tube magazine from the side gate. Capacity would be limited given the length of the cartridges (particularly for .410 shotshells) but it would be fun as hell.
A long barrel version would be cool too - better capacity and sight radius, and you would be able to sell to the US market no prob.
Anyways, here's a crappy MSPaint edit I did... Think about it:
