As long as you don't plan to add an optic, I'd recommend a Williams WGRS sight.
It'll mount on th receiver, using the holes already drilled and tapped for scopes.
Williams WGRS-336 Guide Receiver Peep Sight Marlin 336 Lever Action Aluminum Black - MidwayUSA
Cheaper at Brownells, if you have an account:
"WGRS" RECEIVER SIGHTS - Brownells