I also think that in the '50s Topps was not really a printer, but more of a bubble gum producer and card designer. I believe they farmed out most of their printing to different companies that used different card stock etc. I in the minority by far with this opinion though.
If you watch this video produced by Topps produced circa 1967, they do not show any printing presses, etc. but show stacked printed product, wrapper rolls and assembly operations. Their manufacturing is relegated to bubble gum
Topps Chewing Gum, Inc.: The Hidden Treasure "movie":
https://www.youtube.com/watch?v=lfvCFFBnWic