FWIW, I excavated my 1970 slides & negatives and made quick and dirty (literally) scans
http://www.virhistor.../glen-70-01.htm
This was always a great weekend because it was a chance to see Group 7 and Group 6 cars running together,
I still have 1971-75 races to scan and maybe some day I may actually clean them up.
But at least I can look at them now (and you can too if so inclined).
Cheers,
Nick
www.virhistory.com