It may not be possible to find a ready-made match, especially with Testors pulling the railroad paint lines.
I would try mixing a match. The following would be a couple starting points.
-Equal parts BN green and Penn Central green.
-3 parts BN green, one part blue (say D&H or GTW), maybe one part white.
With a green, a blue, and white and black you should be able to get it. Maybe a yellow if it gets too blue.