It'll work OK with the OEM GPR front sight, although the blade may be a bit thick for the small aperture disk. If you use a center bull hold you may want to switch to a 6 o'clock hold, but I'd think you could get used to it pretty quickly.
I've been considering that same sight for a while; I'd really be interested in what your experience is if you decide to go ahead.
I use a ladder vernier with a large aperture disk and the OEM front sight on my percussion GPR for long (over 100 yards) ranges, but switch back to the open sights for closer work. I like the fact that I can just fold it down to go back to the OEM rear sight.