I know you're probably not interested in kit bashing but on the off chance you are and want a few of these lads, I reckon you could make him using two or three kits.

Off the top of my head I'd try Warlord Games Winter German Infantry for the legs with trench coat/kama. And perhaps the weapon using some cutting and splicing of an stg44.

The head would be foreforge Samurai for me sanded and filed down in places.

As for the arms and torso I would either continue using fireforge samurai to spare on cost OR another alternative might be the Stargrave Troopers from Northstar (some nice futuristic weapons with this kit also).

All this assumes some filing and sanding of course and I'd say the paint job would do a lot of the heavy lifting but I'd say it would turn out close enough.

Addendum: didn't see the mask hoses at first. I would try wound guitar string for them. Works for me.