If you have a blade front on the barrel, but an adjustable rear sight, grind off the blade or jerk it out and drill and tap the barrel for the ramp front sight.
If you want to build a rare gun, install a 4 5/8" ramp sight barrel on an adjustable rear sight frame (Super Single Six).
Or a scarce fixed sight gun (Single Six), install 4 5/8" blade front sight barrel.