I dont remember the sight you are speaking of, but I would make modifications to the sight, not the rifle. There is one silver lining on a model 60 reciever though. It is aluminum or something close. It had a black finish applied instead of bluing. I have touched them up with a black felt marker and paint sticks.
I don't think I would recommend gluing, expoxing, or the like, as you might not want it there permanently. Also, you may want to consider your finished height - will it match the front. The rear sight plane would have to be nearly down to the top of the reciever, to make this work, without changing the front sight.
Not sure that was much help, but it sounds like some of the projects I have tried. Some worked, some didn't. Let us know what happens.