BTW, EAW now offers a much more streamlined pivot mount for the split bridge Mannlicher-Schoenauers, their Pivot Mounts with Lever release, see their online catalog:
http://www.eaw.de/assets/files/2014/EAW_Katalog_2014_Web.pdf , low on page 60.
Here the rear base is offset, just like on the more common three-feet claw mounts. So the rear base is out of sight, but the front base, if mounted on the receiver ring, may still cover the fatory open sights. Maybe it will come a bit less expensive than a claw mount. NECGC may offer these mounts too.