Just as a point of interest, look closely at any original paperwork on your GT/CS. "IF" your paperwork states a particular dealership that sold the car, it might not be the actual dealership that it was sold at.
Dealers; usually in the same local area "trade" cars all the time, and since, in some cases, the CS didn't sell well, some cars may be listed from one Ford dealer, but it was sold through another. Also, there are two or three Ford dealers owned by the same parent company.
I don't mean to undermine the Marti Report, because he works with what Ford provides. But after the dealership has bought the car (and it's on paper that way), anything could have happened.
IF you have paperwork with a specific dealer listed, and no reason (or evidence) to question that information, then go with it. I am just tossing a bit of reality with how dealers "deal" back and forth.
On another note--I think it's great that folks out there are looking for dealer plate frames for others' cars from outside the original area. Swap meets are a good place to find those 1968 vintage metal dealer frames.
Paul N.