the closest match to cgw maroon as as areadily available paint is modelflex's soo line maroon. its the closest thing you can get straight outta the bottle. your other option is lightening up polly s EL maroon with santa fe red. like the NW, the cgw didn't use a constant color, they used several paints by several manufactuers throughout the years. there is historical confirmation that the maroon cgw tank cars were actually painted with the same dupont paint that soo line used. my friend has a couple models that were painted in actual cgw paint. the most poular shade of cgw was actually more of a burgundy when freshly appied and its very close to the modelflex soo line maroon and my friends models prove that.
I am not up to speed on the current availability of model paints so this may be of limited use to you, but the October 1998 MR had a paintshop feature by Jeff Wilson on painting CGW F3s, which were in both the maroon and pure red.
His recipe for maroon was 6 parts Polly Scale PRR Tuscan (414167), one part CSX Blue (!)(414221) and one part Reefer White (414113).
The Testors website shows these colors as still available.
http://www.testors.com/category/137370?n=0
Dave