I always heard the factions referred to as Barts and White Shoes. I think there was a gang in the Mission that affected the Pat Boone look.
In the late '50s the Jesuits even made us wear belts with beltless pant which had recently come into fashion. It looked silly to see guys wear belts with pants tht had no loops, but it was even sillier to argue with a Jesuit.
I had a good friend who went to Mission and it seemed the Bart/White Shoe friction was about as deadly a the S.I./S.H. rivalry.