The leverlution loads are pretty hot. they are designed to get the most out of the old warhorse cartridge. Suggest regular Remington or Federal 45-70 loads. They are the ones for the old trapdoor guns and are milder. Also the lighter the bullet the less recoil, so go with a lighter bullet. It does not take much to kill a deer, and the slow 45-70 is more than adequate.
Good luck, and get a recoil pad for that steel butt plate.
If you reload, check out the loads used for the Cowboy Action Shooting. They are now using Trail Boss a lot, and it is a very mild powder. I use it for subsonic loads.