I'm looking at a thumbhole during-ban AK.  I'd only be interested if I could put on a pistol grip and normal stock.  Did the thumbhole stock affect the US parts count?  IIRC it did, but I'm not up on the parts count regulations since having a FAL built 3 years ago.  (I checked the FAQ under "AK reference" but it was a dead link.)

AKs have only 16 countable parts at max. This is for a stamped receiver with threaded muzzle. You need to replace 6 of these with US parts, which isn't too difficult. US FCGs are easy to find, as are US stock parts, muzzle devices, and gas pistons. Mag parts are pretty easy to find as well, but with the other options, I like the idea of parts on the rifle better than mag parts. Check out the Build it Yourself section for a bit more info, as well as "how tos" for piston replacement, etc. If you have the right parts, a thumbhole conversion is easy, and can be done in an hour or two. The FCG takes about 15-30 mins, depending on if you've done it before, and if you have a good walk-through available. Good luck, and it is a lot of fun to do.

You can convert a thumbhole rifle for less than $100. A Tapco G2 FCG is about $30 and a U.S. made Kvar stock set is about $65.

Quoted: I'm looking at a thumbhole during-ban AK...

Please be aware that some ban-era thumbhole-stocked AKs have a blocking plate instead of an opening at the back of the receiver and are not readily converted to PG/standard-stock configuration...

If you get a Kvar US made stock set you get 3 US parts.If you don't have a threaded muzzle you could buy US floorplates and followers for all your mags and leave the excellent FCG alone.
You also could thread the muzzle,and install an  American device.
As the other posters say you can always ad a US gas piston,there is another changeable part.
I have converted a couple of MAKs and am going this route with my latest AK a NHM 91.
I just think replacing the super slick FCG is a crying shame.
My .02.