The 86,000 M1rifles form the Philippines rang from awful to really nice, same is likely true with the Vietnamese m1 carbines.
On does not really know, does one? My post was to point out 1.5 million figure is not really correct, given the last 42 years since the war it is likely on a small fraction could be imported. I note the link you showed indicated some might not be US property, which would simplify the import process a great deal and if not on the US inventory for 1975, might indicate the survival rate as much higher than 78%.