Here’s some scans from a box of slides that are probably from about 1965. They feature pictures from Marineland and Sebring. I’m unsure of the exact dates. The pictures of Spirit of America reference the record breaking run in 1964.
Marineland and Sebring
I found the race sheet for that day, March 27, 1965
https://www.racingsportscars.com/photo/Sebring-1965-03-27.html