I have been thinking about this since I read it. If it were mine and I was doing a rebarrel on the cheap. I would just fill the holes and redrill for sights. One could could make a bit of tapered screw to tighten and cut off flush wich will almost disapear when cut and filed to match barrel. Holes could be accra glassed shut and barrel painted black or camoed. I worry more about performance than looks.
Jay