Just get an afternarket stock and handgrip.
Lotta imports need atleast 6 pieces to be 922(R) compliant so depending on whick AK you have you might be performing an illegal mod if you only replace a couple pieces.
Here's a good resource.
http://922r.com/
Where as if you own a mak90 sporter post ban you only need 5 US made parts to be 922 (r) compliant because the lack of a threaded barrel in post ban sporter models resulting in the removal of barrel acessories as part of the compliant parts .
ex. a us made stock , pistol grip , upper and lower <count as 1 US copliant part > , tapco magazine < counts as 3 compliant parts US made body , follower and floorplate >
Those replacement parts count as 6 pieces which for ak 47 would make any modded AK 922 (r) compliant . Although that just represents 6 out of I think 16 possible parts you could replace. The 6 I listed are the easiest to do.
Basically the rule is Unless the weapon is stock and unmoddified you may have no more than 10 original parts on said weapon . There is a different count of US made parts needed for several different classes of weapon
Take the AK and the SKS for instance. As I stated you need to replace 6 parts to be 922 (r) compliant on an AK because there are 16 possible parts you can replace.
But on a SKS there are 17 parts that can be replaced to make a 922 (r) compliant weapon so your count to meet the " No more than 10 original 922 listed parts " could constitute atleast 7 stock pieces needed to replace to make a compliant weapon
All that being said. I am not aware of ANYONE being arrested for possesing a non 922 (r) compliant modded weapon. But I wouldn't wanna test it.