It never came to pass (obviously), but Barry Sheene was down to race a Ducati 750SS at the '72 Imola 200 Miglia. This was the race that his brother in law Paul Smart won, setting Ducati on the path of big-bike racing success that's been a part of their DNA ever since.
This comes from Livio Lodi, currator of the Ducati museum. It seems Sheeney was approached, and in those lawyer free days the printers were told to include his name on the programme. In truth he decided he'd be more likely to win on a Trident, presumably in a Rob North frame, but Triumph's cash tin was bare and Barry was a no-show.
Ducati was also chasing Pasolini and Saarinen, but like Sheene they probably doubted the Ducati would be competitive. So Smart and Spaggiari made the history books, and ever since then Ducati have been able to cherry pick their riders. Long may it continue
(And thanks Christian for the excellent pic)