Hi Tom,
Imagine seeing you here!!! I personally know of a '69 442 W-30 that was painted in Chevy Rally Green. I also know that currently Ford has DSO colors (Dealer Special Option). Only requirement for this is that they have an order for at least 5 of a certain color and pay the necessary dollars to do it. I would assume that the General had something going on like that for fleet and special orders back in the day. I will see if I can tap some of my resources for vintage colors to see if anything pops up!!!