Sabrewerks has been making a very indigenous optics mount that replaces the Kalashnikov factory rear sight blocks. The initial unit requires some gunsmithing or least knowledge of complete Kalashnikov disassembly (removing the OEM rear sight block). Once this is removed, you now have a system on which to insert a variety of optic platforms made by Sabrewerks onto the mount. These are held in place by a very snug dovetails on the base mount, in addition to a cross pin that doubles as a gas tube retaining pin (previous retaining pin is removed with the old rear sight block). The company makes a mount for just about any optic you want to throw on the rifle, and I’m sure if you have an older scope, they’ll be able to do a custom fit for it. Every mount they make has an integrated non adjustable rear sight within it, so if the scope goes down, there will always be a back up rear sight, without the need to affix an aftermarket rear sight. Of course, this does take away the ability to co-witness a rear sight (However, some of their reflex optic mounts do allow for a co-witness). In addition, an important point about their system is that it allows removal of the top cover for disassembly without needing to take off the optics mount first.
The company is a small one in Wisconsin, and has been around for the past five years. I’m honestly surprised I haven’t seen one of their products up until now.