You need to keep the imported parts count down to 10 or less. From memory here are the parts that count. You can mix and match parts just as long as you have no more than 10 imported parts on the rifle. So if you replace say the floor plates and followers in your imported magazines, you just cut the total imported parts by 2. Since the FAL has no trunion you can eliminate that part from the list. Of course you need to know what parts in your rifle are US made so you know where you are at this point.
I may have missed one or two, to go FALfiles.com and you can get an accurate list.
Barrel
Trunion
Receiver
Stock
Handguard
Gas Piston
Muzzle attachment (flash hider, muzzle brake, etc)
Magazine body
Magazine floor plate
Magazine follower
Hammer
Trigger
Sear