How about Crossover Miniatures Super Soldier with a US helmet head?
This is my modern version using one of the supplied heads, it should take a Westwind US helmeted head or other ones.

A note, I had not heard of Jeffrey Mace.
I am in the process of adding one of Hasslefree's Hoplite shields to their Stephanie Rogers figures (and swappiing the Thompson for a BREN).
Scale wise: Crossover, Crooked Dice, Crossover, Crooked Dice, Crossover

Westwind US helmeted head on Crooked Dice Minion Commander body.

That might also be of use.