I suspect you’re talking about the front sight. Midwayusa and Brownells should have what you’re looking for.
As far as the rear sight there’s a couple options all but one of my lever action center-fires have steel aperture sights -maybe one aluminum, I don’t remember.
If you buy a aperture sight that mounts on the receiver all you’ll need is a couple of threaded holes.

I prefer classic.
Semper Fi
I used to run with the hare. Now I'm envious of the tortoise and I do my own stunts but rarely intentionally