The green should be very dark, described at the time as " almost black ". I use Vallejo Black Green 70.980 , and add Dark Prussian Blue 70.899, and then a dash of red. You might need to experiment a bit on a palette to get proportions. My basic premise is that it was the same dye mix as dark blue, ie Indigo, with yellow dye ( almost certainly Weld) added.
At the risk of beefing on about a personal obsession, dark blue uniforms at the time were also very dark, though you would hardly guess that by looking at most wargame figures.....and the Dark Prussian Blue most people use for dark blue should be darkened by adding red.
Works pretty well.