I've been running the "stock" sights that came on the rifle. It's been used on three deer hunts and scored three times, so I can't complain.
Those Marbles sights are very well made, easily adjusted, present a clear sight picture, and are very appropriate for an octagon barrelled "cowboy" rifle. And, that 26" tapered octagon barrel gives plenty of sight radius and steadiness for accuracy. The 24" - 26" barrelled lever action rifle seems to have been the most popular big game rifle of it's day before WW1.
I learned to shoot one-handed duelist stance using a target pistol to shoot bullseye targets at 25 yards before I ever shot a rifle. So transitioning to open sights on a rifle was easy.
Millions of shooters and hunters never used anything else back in the day, and always got their deer, elk, or moose. Some had tang peep sights way back when, and receiver sights were introduced in the 20th century as well, but many did not ever use them.
All it takes is a little practice and young eyes and these sights work fine out to 100 yards or so for just about anyone.