I have a #3 in 45-70 and a Marlin 1895 in 45-70. I love the #3 simply for the style of the rifle. It is quite accurate but with hot loads it is very unpleasant to shoot, not an issue with trapdoor loads. The 1895 is much more pleasant to shoot, just as accurate, but not quite as handy. If it were me I would opt for the 1895 but in 45-70. The 450 is a one load cartridge where as the 45-70 will top out with the 450, remember the big selling point when the 450 came out was that it was the factory equivelant of max 45-70 handloads. 45-70 brass is cheaper and easier to come by and I suspect will be with us as long as the metallic cartridge. I don't know if I would say that about the 450. Actually for the animals you have specified the factory (trap door) 45-70 loads will serve you well. But both rifles are great firearms and you will enjoy whichever you choose