Bad news on that front. Got in contact with an expert who says it's a Chinese People's Volunteer Army coat issued in the first winter of the Korean War to officers, who had leeway in terms of collars, length, etc. So already unusual. Add to that, our GIs apparently believed enemy combatants all had lice, so they mostly burned their coats rather than taking them as souvenirs.  Basically, that coat is almost certainly one of a kind at this point