I believe you dont need us parts as long as you keep the thumbhole stock, and the magwill is thin enough to only accept single stack mags. thats how the romainan wasr-10 single stack rifles are. only problem is the stock set which comes with the bulgy kit, (and barrel in its current threaded form) will not work on anything but a milled receiver. so your options would be:
1. buy a milled receiver, and a us made fcg (only 3 more parts would be needed assuming the receiver is us made)
2. buy 2 new trunions, a thumbhole stock designed for stamped receiver, turn down barrel threads on a lathe, and fabricate a receiver that can only take single stack mags. The reason I say fabricate is I dont think there is anywhere to buy a completed receiver in this form without buying the entire rifle. While this isnt a very practical option it is the only one requiring no us parts. The receiver would be us made if you made it, but technically you could travel to canada, build it, and assemble it
3. buy a complete akm receiver or make one yourself, get 2 new trunions, a stock, a us pistol grip and fcg. This way you could use double stack mags, have a pistol grip, basically have a very nice akm with the only problem being that you would have to turn down the threads on the barrel.
Probably the best option would be to get a milled receiver, but this is quite expensive. $389 if i remember correctly for the firing line one. the build however would be very simple. Slightly cheaper would be the stamped option.