Fencer,
THe VVS site is the most authoritative I have found, the analysis of the colors is the best around. They've got Russian color chips, too. The Airacobra I should be standard RAF green/gray camo, earlier P-400s were sand/spinach, also standard RAF scheme. You should be able to use the standard RAF fighter template.
If you look carefully at the picture of White 67 in Osprey 36, p82, you'll see the tail behind the stripe is a different color than the rest of the airplane. I think the forward part of the aircraft is Russian green and the tail is OD. Just MHO. p73 of Red Stars 4 has a clearer picture of the aircraft where the foward fuselage is obviously a darker green than the tail. The vvs site sees it differently, there is a discussion of this aircraft on this page toward the bottom:
http://vvs.hobbyvista.com/Markings/P39/color_mark_1.phpAlthough sources indicate US delivered P39s had red stars on the upper wings, I have several photos of P-63s that do not, indicating Bell figured it out at some point. p72 of Red Stars 4 shows a P39 with an upper wing star, but the photo is captioned 1948. I think the majority of the early deliveries had the upper surface markings painted over.
I have Red Stars 1 and 4, Osprey 36 and 74, P39 Detail and Scale and couple of other books, and I know I have seen a picture of a Russian ace signing an autograph on the wing of a P39 where the US star has obviously been painted over with a Russian star ( but I cant find it at this moment, of course, I'll keep hunting ). I'm with Greebo. In 99% of cases paint out the British/American markings with the nearest Russian color, but no red stars on the upper wings.
Last, of course, never trust a drawing to be accurate.
I intended to do the sand/spinach, a gray/green and the overall silver P-39s, but I just don't have time at the moment to attack them. I've been working on a base template for a while, but I'm just starting. Good luck! If I can find some time, I'll scan some examples for you.