Amy Welborn has a Substack site on the experience of being Catholic in the years after Vatican II.
Here is a post on music during the time:
First, the use of secular music, not so much during Mass (although that might have occurred), but in reconciliation and prayer services and retreat days, and as prayer prompts and mood-setters in religion class. All the time, and nothing but. Except for Hosea at reconciliation services, natch. I think it was in canon law, the use of Hosea. Most popular? Bridge over Troubled Waters, You’ve Got a Friend (James Taylor), Blowin’ in the Wind (of course), for some reason, If and Diary (Bread), and Lonely People by America.
Also: (I’m adding these after a reader mentioned them on Facebook - headsmacking moment: how could I forget?!) Turn, Turn, Turn (that was very popular in school services), Morning Has Broken (not surprisingly) and yes, Let it Be.
Now, of course, this was the era of Jesus Christ, Superstar and Godspell. JCS was waay too daring for consideration for any use in my school, but even though the lack-of-resurrection was problematic, Godspell was approved. We sang Day by Day a lot at Mass, and, of course, Prepare Ye went Advent rolled around.