If they are on the left side, a Williams aperture rear sight should just bolt/screw on.
The sight designated for the M94/336 should be correct.
If you call and ask for the screw hole spacing, this should help if you don't want to just order the sight.
Screw hole spacing is pretty much standard with all the side mounted guns.
The sight for the lever guns, has a flat side, whereas for Mauser or other rifles, has rounded contact surface to fit the action.

https://www.midwayusa.com/product/583902...-aluminum-black

The Lyman sight is nicer, but of course, costs considerably more. It has a spring loaded quick release button.

https://www.midwayusa.com/product/716636/lyman-receiver-sight-66a-winchester-94-aluminum-blue