.45-70 is available in several different power loadings. SAAMI pressure is commercial ammo. Think classic 405 grain flat nose soft points at 1300 fps. Safe in old trap door Springfields. But, many modern rifles, including Marlin .45-70 Guide Guns can handle the intermediate and maybe the .45-70 "Magnum" loads intended for strong single shit rifles like Ruger #1 or my H&R 1871 Buffalo Classic. Buffalo Bore 405 grain ammo leaves that long barrel at 2100 fps. That is 4,000 ft. lbs of energy. That is elephant gun range. I use this for deer hunting during our "primate weapons" season which limits rifles to old straight wall case cartridges, including .45-70, in exposed hammer single shots. I don't need the extra energy for deer, but the higher velocity means a flatter trajectory and just about doubles the effective point blank zero range.
The rifle wears a Burris 2-7x35 illuminated reticle heavy duplex, center red dot scope, kept down at 2x 90+% of the time.