Another thought. Jim Carter apparently has the modern PPG codes for the stock colors. At least they sell paint mixed to what they claim to be correct colors, including Windsor Blue. The paint they sell is PPG Performance Coatings Acrylic Enamel. But I doubt they'd share the codes with you as they want to sell you the paint. Unless you catch them in a benevolent mood.
They do have quarts in stock that you could buy for spray-outs.
