Somewhere in the back of my safe is a 30-30 lever gun that's unfired! I have two .444's and a .450. All Marlins. The 45-70 never done much for me, but if you like them then so be it. The .444 shoots much flatter than most folks realize. Will drop a 300+lb. boar dead in his tracks erffortlessly. I have not shot any of the "leverultion ammo" in any of mine, so have no comment there. But a factory loaded Corbon is really a beast in them!! In the .444, stay away from the 240 grain hollow points, and they are thin jacketed and tend to come apart. I like the 265's and 300 grain solid nosed bullets from Speer. Corbon does a 330 grain bullet, that generates some serious recoil in the .444. I used to carry this load when I went on fishing trips up in the Bear Tooth Wilderness, but now take the .450 (very serious recoil) , but I fell safe with it. I can get similar ballistics out of the 45-70, but the loads are pretty hard on the action.
Now what you want to be looking for is a good used Marlin built lever action (not Remington!!). The Winchesters are not as stout. Your choice of sites is up to you, but if shots are 100 yards or less the red dot is a good choice. You want something that has a lot of eye reliefe!! The best bullet I've shot in the .444 is the Barnes 275 grain bullet. They'll print sub 1.30" groups without much trouble, and have heard of a couple that shot MOA groups (mine won't). The downside is that most .444's don't like cast lead bullets (no biggie for me as the velocity will cause massive leading in the barrel).
gary