What is the absolutely correct blue engine paint color for a 74 Duster?

Guys/Gals: I'll be pulling and repainting the slant six motor in my 1974 Duster soon. I've seen many versions of the blue paint used to repaint these engines, so which one is the actual correct blue paint to use on a St. Louis built 1974 Plymouth Duster? Seems like when I go to a car show, every Duster, Dart or Valiant has its own unique hue of blue paint. Some is glossy, some matte and some flat. There isn't any original paint left on my engine, so I have no point of reference, unfortunately. Does anyone out there know what the exactly correct factory paint was? Do you have a Sikkens or Ditzler code? Any and all ideas are welcome, along with your photos of your engine paint. Many thanks!