Seems you've decided on 45/70, guess I agree there. There is notihing the 450 can do that the 45/70 can't with handloading. I think PMC has come out with a pretty decent 300 gr. load, that is quite a bit better than the other big MFRs standard offerings.

My only advice to you would be to get a rifle, and not a guide gun. I have the 1895 SS with a 22" barrel. I just like it better than the 18.5" barrel on the guide guns, mine has a better feel, more velocity, and probably less recoil with the added barrel length/weight. One more thing, no ports on the barrel. If you're thinking about guns in this class, you can't be too scared of some recoil. The 45/70 isn't all that bad. Get the gun first, and if you need to tame recoil, go with a better pad, not ports. Them's my $.02.