There's a guy named Mike Otte who runs a company called Michael's Machines (also does HK belt-fed work) who makes receivers that accept AK magazines and drums that feed AR-15 uppers. The lowers look like they accept standard mil-spec parts except there's no bolt release lever and your mag release is also, obviously, a lever. You'd have to contact him for specifics.
The website for the product is as follows:
I'm sure that's not the only AK mag AR lower out there, but it's one example. The LAR-47 that Rock River sells has the mag release inside the trigger guard. The 47 lower made by MM has the lever in front of the trigger guard. Neither have a bolt release lever.