The first copies of the
WS-MCR in 7.62x39 have finally arrived and are in stock at Wolverine. I suspect they have sent stock to other retailers, as well.
Not an AK OS, but they've addressed many of the issues found in the WK-180 produced previously when applying the 180 OS to a modern rifle. You can't use AK mags (yet, they are interested in an AK-mag accepting lower at a later time, when the world isn't in crisis), but you can use 10 round XCR Pistol magazines. It can take AR15 stocks, drop-in triggers, and pistol grips, so it meets part of your customization requirement.
It would be a new rifle in 7.62x39, but an upper for both the WK lower and the NoDAK Spud lower was previously made by Range Warrior Accessories, before they sadly closed; I don't think too many were made, but I saw no reports on CGN about problems with that upper. Both the RWA upper and new WS upper added steel wear-resistant plates for the bolt to ride against; this should help with the aluminum upper wear issues found on the WK.
Good luck with whatever you decide!