I've built up two ARs from a pair of Norinco lower receivers I got from Joe Dlask. After he hard anodised the lowers, they looked pretty decent. I put in Armalite lower kits, and used the original buffer tubes with an ACE and a YHM skeleton stock. I have no use for the collapsible AR stocks so never cared about the thread pitch issue [Non metric tube screwed into metric hole means weld! ]
If you really want to do this, Joe Dlask can rethread your lower to take the standard pitch buffer tubes.
I used Oly Arms flatop uppers, which usually fit TIGHT. One is in .223 with a 14.5" Dlask hvy barrel, scope AND Eotec mounted on a full length OLY handguard, Phantom flashider, VFG, etc. Looks and shoots about the same as any of the dozens of other AR 15s I've built from kits. One advantage is theat the NORC lowers have the mag wells hogged out properly to take the Mil Surp plastic mags ... not all aftermarket lowers do.
As usual, your mileage may vary, but I am very happy with my two Norc/US bastards.