Several years ago, I bought the Smith Ladder sight that fit in the groove for the rear sight. It didn't work out at all for me. You cannot move the sight up and down and repeat the previous location. I found that one click up was too high and one click down was too low. I wanted to be in between the two clicks.
When you set the elevation you must tighten the set screw or the sight will move up and down the ladder as you shoot. So, if you want to change to a close in shot and you are set for a longer shot, you have to have an allen wrench to make the change.
I sold it.
I would keep looking if I were you.