I found the original photo used for Reds BR. It was part of the Sporting News Collection. So an easily identifiable type 1 photo. I personally don't think your blank back photos with the names written on the front were used for the cards. But I do think they were some sort of issue.
99% of card used images have press markings or team markings (file dates, team copyrights, etc,) I'm only saying 99% and not 100 because anything is possible, but in my experience I would never buy a blank back photo thinking it was used for a card.
