Ford did make kits available for dealer installation but they also included many factory produced cars reference 1957 "F" code passenger cars and T-birds. I don't know about the dealer installed kits but the factory cars had special heads which made putting a used kit together a little harder. There weren't many F codes produced (notice value of F code T-birds today). A friend of mine had a 57 2dr sedan F code he raced in the NHRA stock classes. Your're right about kits for various cars this units history goes back to the 30's but relatively speaking there were not many factory cars produced with the supercharger
