I think this could work good, but as you said, I am not sure how much room is left to drill and tap. As soon as I find a spare set of irons I am going to look into this.
That's not a bad idea if there is enough room. I think Williams makes a rear peep sight with thread in aperture's. If you could find one and thread it in you'd have a sweet sight. Wouldn't be able to flip to any of the others but they probably wouldn't be needed any more.


















































