That pic with Dean Lowry is the original steel door. The Inch Pincher was a '56, the fiberglass door found was based off of a '55 and earlier door. The big back window was grafted in when this fiberglass door started being used.
I would say the ribbed 'glass doors were used before the roof was covered with the material. Which by the way, had to be done to cover all the paint, and filler that flaked off when the car was in a very cold part of the county overnight, Kansas?