I use 405 gr. hard cast gas checked wide flat nose bullets.
As far a peep sights, your better off with the iron sights. Low light you will not be able to see through the peep sight.
Myself I like low magnification scopes. My Marlin 1895 45-70 has a Leupold 2x7X33 scope, my Marlin 1894 44 Mag has a Leupold M8 4X scope and my Marlin 444P is getting a Leupold 2.5X20 scope.
The reason I went to scopes was, low light conditions on my black bear hunts. My very first hunt I had for black bear, I used my 45-70 Marlin, the bear came in about 10 minits before shooting time was up, I could not see my sights when I pointed the rifle at him. So I did not take the shot. The next day I went into town and bought a mount, rings and a Leupold scope, and sighted the gun in at 100 yards, that night hunting, the bear came back into the bait and I took him.
The scope makes a big difference in low light conditions.
Now I do like open sights on my lever guns, but I now perfer a scope for the reason stated above.