A 45-70 in a 16" Contender would be..... sporty.
You're right about that................ the pic further up of the 'Mushrooms' .... they were shot out of a Marlin Cowboy Gun, 26" Octagon Bbl, yadda yadda.... 500grns loafing along at about 1600 fp, it was close to 'sporty'..... that might be a bit too stout for the Contender frame though.....