Matching skin colors to those shown in profiles is often frustrating. The artist might know what RLM color he's trying to show, but like everybody else he has his own idea of what the color actually looked like. In addition, like everybody else, the profile artist often varies that color from his "best source" info to make it "look right" (to him, according to his own preconceptions and biases) on the finished profile. There is no guarantee the profile artist is right, and therefore copying him is just copying that artist's artistic interpretation, while including whatever changes he made in the color to suit his own tastes and the medium of the profile, as opposed to a skin.
This being the case, it's probably just as realistic to use your own judgment as to the colors. A good place to start is with some general assumptions, such as what paints were most likely to be available to units in the field. The answer to that is the standard RLM paints, although they might have had some captured Russian paints as well. Then you pick the RLM colors that most closely match what you see in the profile, and if none come close enough to suit you, see if any Russian paints might do.
The basic assumption is that the plane arrived at the front in the then-standard RLM 74/75/76 scheme. The unit repainted at least the upper surfaces, maybe the lower as well. There are several possibilities within the general framework of using what was available.
1. The dark green shown is just the artist's rendering of RLM74, which was for a long time thought to be a dark gray instead of a green. Batches varied in darkness over time, too. Anyway, they used their on-hand RLM74 and either RLM 79 Sand Gelb stolen from somewhere, or perhaps captured Russian AII Light Brown. The belly remains RLM 76.
2. The dark green is RLM 70 or 71 stolen from a nearby buff unit. The brown is again either RLM 79 or AII Light Brown. The belly could be RLM 76 or perhaps even 65, also stolen from a buff unit.
3. The unit somehow got large quantities of the German desert paint and used RLM 79 and 80 on the upper surfaces. The belly could still be RLM 76 or perhaps the desert RLM 78.
Given that large numbers of Ostfront planes sported brown in the camo, I think that captured Russian stocks would have been insufficient, especially after the 1st year of the campaign. Therefore, I'd bet that a lot of RLM 79 and 80 ended up on the Ostfront from 1942 on, especially because of the drop in demand for it in North Africa about that time. If I were doing this skin, therefore, I'd go with option #3, including the RLM 78 belly.
