Great idea!
Some possibilities:
Red Helmets & Jerseys, White Pants: Wisconsin, Alabama, Indiana, Louisville (can go with white jerseys as well)
Gold Helmets, Black/White Jerseys, gold pants: New Orleans Saints, Purdue Boilermakers (my alma mater!) I’m not sure, but Georgia Tech and Vanderbilt may work as well
As you noted, Pittsburgh Steelers = Iowa Hawkeyes (white and black jerseys)
Purple helmets & Jerseys — Minnesota Vikings & Northwestern Wildcats
I know there are more but they’re not jumping out at me at the moment. If I think of more I’ll post them.