You could just change the aperture, but that's not the problem with these sights.
The elevation and windage are the problems, since these are threaded metric, you can't use the Norc base once you switch the knobs.....but you could use the norc aperture and the spring cover, those are the only parts that are usable. GI apertures are $10 - $15 so you might as well change it while you're at it.
GG&FB