I think the 350 grain Hornady round nose or flat nose is a good bullet for any thing in North America and I have shot them quite a bit. I have used the 405 grain super premium bonded flat nose from Alaska Bullet Works here in Alaska because of our big bears. I have about 80 of them loaded in WW cases and when they are gone I am loading up a 350 grain version of the same bullet in new Starline brass.
I have carried and shot a Marlin 45-70 since 1990 and never killed a critter with it. My customized peep sighted and octagon barreled Marlin holds 7 rounds and is comforting to have around for our Alaskan outings. I tried IMR 3031 and RL7 and long ago switched to H322 and WLR primers for all my 45-70 loads. It fills up the case and the bullet sits on the powder and with a good crimp they stay put.
Really hard to come up with a bad bullet for killing with a 45-70 and even a 300 grain hollow point is gonna hurt what it hits.
