Just to be clear, the 45-70 is a taperd case. Not a lot of taper but it is tapered, not straight.
The 350 grain Round Nose is a good choice. Several powders work well. H-4895 kicks it up a notch compared to Varget. 3031 and Reloader #7 have a sharp raport whereas the other powders have more of a push than a crack. You can tell the difference in felt recoil. None of them are fun to shoot off a bench if you are burning through a couple boxes of ammo. The factory 405 grain loads are down-loaded for Springfield type rifles and are mild to shoot compared to what you can do with your handloads.
Snuffy, great pics, thanks for sharing.
Gun control is hitting what you aim at..