The October 2024 issue of Collectible Automobile has an article on 71-73 Cougars. There are many photos in the article, including styling proposals. The articles in this magazine are great reads: they include history and describe changes for each model year among many other things.
This magazine had an article on the 67-69 Cougars in one of its early issues.
BTW I have a copy of every issue of CA since they began publication in the early 80s.