Topps went from 100 to 110 card half sheets in 1954 (not '55, I just realized I have a better scan of a 1954 half sheet I thought was 100 in array). At least one series had differing A and B slits which you can see from the partial below when compared to the very grainy (sorry, old REA print catalog scan) and one of those sheets had the quadrant used for the 1955 Baseball Stamp mockups. I can't find a correlation to the Sports Illustrated inserts in 1955 (or '54 for that matter) and they appear to have been composed in a different manner, i.e. not taken from a specific area on the sheet.
I wonder if we can decipher some more of this? Here's some old blog posts I made that might help:
https://www.thetoppsarchives.com/201...ps-to-win.html
https://www.thetoppsarchives.com/2018/05/stamp-act.html