TCU is a great excuse to go to Texas. The Irish have only played TCU once, in 1972.
We haven't played Houston since 1978...and that was a pretty good game. Similarly, Florida in '91 was a great game. That would be an interesting team for a home and home.
Tennessee is another SEC team to schedule. What about the Mississippi schools? We haven't played them recently.
Colorado or Kansas State might be interesting adds to the schedule for home and homes. Missouri, South Carolina, Cal.
I'm looking at this site for FBS schools we haven't played in a while.
Link: https://www.sports-reference.com/cfb/schools/notre-dame/head-to-head.html