Thanks, John (@johnb). I did a little research into colors for this plane, especially the interior. As you might expect, the Soviets were scrambling during the early years of the war trying to survive. They had standard camouflage patterns for planes, as well as standard colors, but there are many instances where they used whatever they could get. The plane I chose was a late-war plane and it appears that they actually used standard colors and patterns. The standard colors in this case are AMT1 (Light Brown), AMT4 (Green), AMT12 (Dark Gray), and AMT7 (Light Blue). There will be a faded black or dark gray coat over the standard colors, but black is usually easier to duplicate.
The bigger problem was the interior color. A short trip through the internet wasn't very helpful. The interior color was reported to be light gray, blue gray, silver gray, pale green, or natural metal, all depending on the source. As near as I can tell, the color listed in the regulations was silver gray.
My preferred paints are AK Real Colors, so I checked their list of colors and found all of the required colors in their lineup, including A14 Silver Gray for the interior. My biggest surprise of the day was when I went to my local hobby store and found they had all of the needed colors in stock. Yeah.