I see John Fallon (similar surname to the Ducati author, but NOT related), has this one for sale in the UK. It has been restored and does look very good, BUT at £5,000, I find it expensive, even without the trans-Atlantic shipping. I guess the owner (John often acts as an agent for owners looking to sell) is trying to recover some of his restoration costs.
(Even tho' it's not a perfectly correct restoration), there are some good reference photos. Go
http://www.madeinitalymotorcycles.com/sps.htm
Ciao
Craig