Wow. Except for the price, that thing looks hella cool. I'd own one in a second, except that I simply won't pay that much.
I've long thought about picking up an 80% lower and modifying the front part. I'm sure it'd be a mess and would take quite a bit of time, but I love the idea of using AK mags. They're just so darn reliable. Probably if I did it, I'd try to figure out a way to cut a slot in the side of AK mags so as to allow "drop free" use with the AR mag catch. (BATF says if you add a mag catch location, but the mag still works in the weapon for which it was designed, you haven't manufactured a new mag).
Hmm... maybe that'll be a project.
Ultimately, I'd think that the first guy to successfully do this would be able to supply some design info stuff to tanneryshop and the others who make 80% receivers. Then they could sell an 80% "ak mag ready" receiver, that would be cast with the right shape and whatnot.