Did a google search for Daytona 935 Challenge , as i had never heard of it. This article from R&T popped up. Some really excellent images of 935s driven in anger seemingly at the zenith of their power...late 70s-early 80s before the group C cars took over.. likely a few owned by Van at some point...
https://www.roadandtrack.com/motorsports/g23506521/porsche-935-1977-1984/
