Charlie, The photo you posted may be the colors of the car I'm wondering about , I honestly do not remember the precise details. 45 years is a long time to carry colors in your head!!
If you keep old issues of Trains (or have the Trains magazine DVD set) look at pp 38-39 0f the March 69 isssue which has photos of the fantrip I'm talking about. The N&W Business car is the second car behind the locomotive (which is NKP 759. First car behind the locomotive is a baggage car). The photos are unfortunately all black & white shots and kind of dark.