Robert:
Pete Dye sent me to Piping Rock in 1986 to run the job there. It was not a restoration; Pete was enamored with the idea the club had room to take one of Raynor and Macdonald's designs to modern championship length, and his son, P.B., wanted to make it harder in some places, such as cutting part of the 17th green away. But we also repaired all of the old bunkers into more of the old style, rebuilt the ridge around the 7th green, and did some other things that were restorative.
Two years prior to that, Pete had sent me to The Camargo Club when they called him with regrets about the work they had done in the 1960's, which Pete had tried to talk them out of at the time. His impetus for sending me there was entirely about restoration, though I did not use that word in any of my reports until years later. We didn't really make much progress on that until several years later, though, so I wouldn't say that project was especially significant in starting the restoration movement. Even when I started consulting at Garden City Golf Club c. 1991, "restoration" was not a word that was used much, but a lot of what we were doing fit that description.
Mr. and Mrs. Dye always said that the superintendent at Shoreacres in the early 80's was the first real restoration work they had seen and liked. Pete was not a big fan of the concept generally, but he was an admirer of Raynor's work and hated some of the things that had been done to such places.
Most clubs in the 1980's had no intention of closing the course and doing a lot of work at once; the restoration process was quite slow and mostly done in-house. My company did a lot of that work in the 1990's when most other architects pooh-poohed the entire concept of restoration: The Creek Club, Shoreacres, Yeamans Hall, etc. Then some of those courses started showing up in the rankings, and lots of other clubs followed suit.