I suggest that you try www.tcpglobal.com for the codes. They have all of the early Ford color chips and original codes online.
I prefer to use PPG K-36 which is a light gray, almost white as a base under all of the colors I spray. PPG does allow K-36 to be tinted so you could tint it Brewster Green to help insure the true color in the final color coat. I suspect that DuPont has similar systems. Gar Williams