The official PRR color is DGLE. We often forget that DGLE is mostly black with a little green mixed. Just like Pennsy steam where the the locomotive boiler, cab, tender, etc. was DGLE with a black chassis, wheels, and undercarriage. If you were to place a 1960's GG1 next to an E44 the color would be the same.
Granted, these are restored in Strasburg, but the locomotives are photographed under the same lighting conditions and the historians there know quite a bit about the PRR. Add some road dirt and it looks black to the eye. 1960's PRR was not an era synonymous with the wash rack. I think model paints tend to bring out the green too much when it comes to DGLE.
Of course you could also paint it for Amtrak 
One got painted in silver and black. Quite attractive even if it never saw service.
Is your casting a Duddy, Alexander, or other? What are you using for Faively pantographs? My unedited photos below and links to web photos under that.
