I have a question. I have a Mak90, but I believe it was imported before 1994 ban. It has a thumbhole stock, but a threaded barrel and Flashhider. The receiver is the one designed for the paratrooper version with the setup for the underfolding stock and solid slanted back of the reciever. If i had less than 11 imported parts on my gun, could I legally install an underfolding stock since it was pre 1994 ban?