When I worked as a smith, we used to mill a slot, drill and tap the ends of the slot, and install H&R sight blades in pistols like that (just like H&R factory adjustable sights). If it was a better gun, I would say go ahead and do it, it will likely run about $100 or so. Add another $50-$100 to that and you can buy a used Ruger Single Six and have a much better gun.
