What was unique / of interest in the Vietnam era? We're on the front end of that 50 year era.
Nothing that isn't already out there, or Class III. SKS, AK, M16. Probably no big warehouses full ready to be sold to the US C&R market. Maybe the M1's and Carbines that have been talked about.
Anything else will be coming from somewhere other than EU countries. Don't they have a program to destroy all military surplus firearms? Just wonder how the Walther P1's and, not C&R, but Sig 225's survived?