Not to take away from remington jims experience, but I don't find the 45-70 recoil near as objectionable as I used to. I'm not a recoil junkie (or recoil shy) but the biggest part is getting it through your head that the recoil isn't going to kill you. Mind you, my Handi rifle has a scope and 10 cartridges saddled on it, so it might be a chubby gal compared to a Marlin. I shoot a fair amount of watered down loads as well. I also have a 458 Win mag, so after shooting that, nothing seemed quite so lively.
45-70
My deer stand/plinker load which is 14 grains Unique and a 405 cast goes 1,175-1,200 fps and feels like a 30-30.
Home version loads with the 325 Hornady bullets (about 2,150? fps) feel like the factory version.
405's going 1,500-1,600 feel like a shotgun slug or a bit less.
405's going 1,800-1,850 fps feel like a slightly angry version of a slug.
500's going ballpark 1,400 fps feel like a slower kick version of a shotgun slug.
edit to add: rifle full up is 8.6 lbs