ModelRailroadForums.com is a free Model Railroad Discussion Forum and photo gallery. We cover all scales and sizes of model railroads. Online since 2002, it's one of the oldest and largest model railroad forums on the web. Whether you're a master model railroader or just getting started, you'll find something of interest here.
You could try C&O blue with some black added to it to darken it. The Norfolk and Western Pevlar Blue tended to fade pretty badly so you really can't get it wrong. But you are going to have to mix to get what you really want.
N&W and C&O were planning to merge, so they started painting their locomotives the same color (blue). So, C&O enchantment blue should be pretty close, especially since blue fades so badly.