Either gun will do and I own both 2 inch guns and 16's. I think the two inch, 12 would be my choice, overall. If you look hard enough you will eventually find the gun that fits your dimensions. Kirby Hoyt seems to get a fair number of two inch guns. One of mine came from him and it has 28" barrels and a long LOP.

Don't let scarcity of ammo be a factor. Just pack enough along so you never run out. I have a friend who once said, "the best hunt you can have is when you run out of ammo".