Considering the role the bison's played in American history and legend, I think I'd have to look at this hunt as an excuse to buy myself a Sharps or Springfield replicain .45-70.

We're not talking about Cape Buffalo here, though. A cannon isn't required to bring one down, a well-placed shot from your elk/moose rifle will do. Both the guys I know who hunted bison in the last couple years did it with a .30-06and .300 Win Mag, respectively. Since I already have a .375, I'd be inclined to take it, but wouldn't feel undergunned if all I had was my .30-06.