Had a 45-70 and got rid of it. Only place I'd use it isinwoods setting at shortrange. Rainbow Trajectory limits it as a short range roundunless you are areal experienced shooter and like extrapolating rainbow trajectories while hunting. At short ranges I see no advantage to the 45-70 over a 44 mag in a lever action and many disadvantages like weight and cost and recoiletc. The 45-70 has seen its day, time to let it die the death it deserves.
See below and then ask yourself if you really want a rifle cartridge that makes a 44 mag look good at 150yds?

http://www.remington.com/products/ammunition/ballistics/comparative_ballistics_results.aspx?data=RH44MGA*R 4570G