I posted this on another site. It was well received, so thought I would share it here too.
Here are some images of how I altered a TC Hawken rear sight to a tang mount peep sight. Disassemble the sight, and then file or grind the back of the v to vertical, instead of angled back. Then prepare a piece of brass to be the peep holder, or ghost ring, if not tapped for the peep threads. The brass piece is then soft soldered, or maybe epoxied to the back of the altered v sight. The sight can now be re-assembled. The base of the new peep is carefully filed or ground ( I used the end of my belt sander)so the bottom of the base matches the angle or curve of the tang. It now requires new holes to be drilled & tapped into the tang for the new peep. HC-PC it is not, but a relatively cheap peep with windage & elevation adjustments. If you use a straight edge to predetermine the approximate height of the center of the peep as you build it, you may not have to alter, or replace, the front sight. Don't ask me how I know.