If you don't like the ghost rings, you might consider a Williams Foolproof. It's an aperture, peep, sight and the peeps are available in many different ODs and IDs. Williams also makes the WDOS dovetail open sight. These slide into the existing dovetail and lock down with a set screw. They are available with different blade styles - square, V, U, or a shallow (express) V. You might also consider replacing the front sight with one that has a fiber optic in it. These really show up in low light. Brownells carries a good selection.