...and paint on the model.
Choice of colours is not so easy with this model - there are very few period colour photographs, the few that are out there create more questions than answers, and verbal information is limited to (in a nutshell) "launcher and missile are green, with darker green spots on the missile". Quite often, it seems that the missile has a slightly different tone than the launcher, even in black-and-white shots.
I think it went like this:
(1) The launchers, transport vehicles, radars etc. were delivered in what is sometimes called "Russian Green", essentially some variation of 4BO, which is itself a somewhat elusive paint that weathers to many different tones. You know it when you see it, but it is different almost every time. So, one is free within a certain range of hues. I have been happy in my builds with a mix of 50% Tamiya XF-49 (Khaki) and 50% XF-58 (Olive Green), and that is what the launcher will be.
(2) The missiles came to Vietnam first in a very light grey and later in (factory-painted) green; it would basically make sense to assume 4BO, too, but this is missiles, not army vehicles, so I just don't know. Even if the missiles were 4BO, too, they would not suffer weathering, as opposed to the launchers, which got a lot of use and tropical weather thrown at them over time. So a difference in tone would be logical. To reflect this, the missile is painted XF-89 (Dark Green 2), a WW2 German tank colour, which is a tad lighter and greener than my home-mix 4BO..
The spots on the missile were (IMHO) painted on in Vietnam, with something whose standard is unknown today, if it ever existed. Even in black-and-white photos one can see that the spots on the missiles are sometimes glossy where the base colour is matt, and they are applied quite randomly with no design behind the pattern. "Put camo spots on this missile, you have [insert tight timeframe]." The spots look brownish on colour photos, with strong contrast. I will use a mix of 50% XF-62 (Olive Green) and 50% XF-64 (Red Brown).
Launcher parts in 4BO home mix:
Missile in Dark Green 2:
...and everything together.
It may well be that the difference in tone will disappear after laquers, wash and drybrushing, but I maintain that it is well visible now, even in the face of family ridicule. 😊
Next step: spots on the missile. Might find time to do them today, we will see...