AFAIK, the WGRS is the only receiver sight with a version made specifically for the BLR ( I had one on my .358).
Have you considered a reflex sight, like the Dr.Optic ?
(although there's many others, like Meprolight/Burris/Trijicon/TruGlo/etc/etc)
A reflex sight mounts and is used like a receiver peep, but is more like a zero magnification scope, in that it doesn't use any front sight.
The illumination, much like that of fiber-optic sights, does wonders both for vision and while hunting in gloom.