I want all matching numbers kit naturally , not any good in paying good money and ending up with a ," johnny cash " rifle . lol
If you're not prepared to build it "one piece at a time" don't bother; just find a Wiselite build to pay through the nose for.
1) The gun was originally open bolt/slam fire operation. You will have to convert it to closed bolt striker or hammer fire (both are well documented) in such a way unmodified parts don't fit.
2) The gun was originally full automatic. You will need to devise a semi-auto-only system, and one that is not easily 'reactivated' (see bolt conversion)
3) The gun was originally short barrelled; you'll need a longer barrel & longer shroud (anteater), or file a Form 1 SBR
4) Gun is composed of import parts; you may need to replace some items to comply with 922r (not as big an issue for blowback guns since so many new parts are US made for the bolt/trigger conversion)
5) Original receiver was destroyed; you will have to fabricate a new one that won't accept original bolt or sear parts
Check out weaponsguild, weaponeer, gunco, and militaryfirearm .com's for many different build journals and great info. Start your own build thread if you're serious about going down this rabbit hole --it's really fun, but quite addicting.