Thanks Pat, sounds like Groves had a connection to Southern California as well. And definitely seems like PCL ballparks were possibly involved in distributing these sets.
I still need to see if I can locate the list of differences between the blue and red back sets that Rhett mentioned. I did find this in-depth article by member Anson that goes into the history of the set and its developer.
https://prewarcards.com/2018/04/23/t...ls-game-cards/
Brian