Actually thinking about it, it shouldn't be too difficult making one yourself.
Compare these:
AK12:
http://i1172.photobucket.com/albums/r561/ak47frizzle/battlefield-4-ak-12_zps4713b328.jpg
AK47 tactical:
http://i1172.photobucket.com/albums/r561/ak47frizzle/Products1325-1200x800-222054_zpsa879492e.jpg
They're not far off are they?
So i reckon these cosmetic changes might work:
Buy a railed version of a dust cover, hammer out the insides so it more blocky like the ak12's dust cover, then you can cut out metal on both sides to have space for the 2 changing handles.
Next you can take out the leaf sight and glue a rail on top of it.
Since the lower handguard is right next to the charging handle, you can cut off some of the body, then you can buy a longer lower ris, cut it to the correct length and somehow mold it onto the bottom and make it align with the body.
Then buy an AK74 flash hider or any sort of flash hider that closely resembles the ak12's and shove it at the end of the barrel,
Then buy some magpul stock that closely resembles the ak12's
Buy some Beta Project AK mags and it should be done... kind of...
It's perfectly possible for someone to convert an AK to an AK12.