I think the helmet size looks right for an ARVN trooper too. The M1 helmet and its liner came in one size. the leather head band and harness was adjustable. On a small person (nationality regardless, but like the average Vietnamese), teh M1 helmet would look big like that.
But, as they say, to each their own!
In my case, that chap, as well as some other of your ARVNs, may just end up as members of the Guardia Nacional Del Perdomo (the GNP). EL Perdomo is my fictional central American country (nestled snugly between Panama and Costa Rica), with games set in 1989.
