I used to have a 160 monza jr. Right now i have a 350 sebring. The singles are pretty cool bikes, especially the desmo heads
The guy I bought these from has TWO Mk3 Desmos (like this one):
One is really nice, the other a little rough. Another friend of mine also has two of them, again a really nice one (in his living room), and a rougher one (although he may have sold that one since we last spoke, as that was the plan).
I'd love to have a Desmo, but, they go for crazy money. Heck, just a Desmo cylinder head can go for $1,500-$2,000.
My friend doing the rebuild has done coil-spring conversions on the springer heads. I may go that route, as it allows for a more aggressive cam profile. I'm going to listen to whatever he recommends, has he has four decades of experience hot-rodding all sorts of motorcycles engines, Guzzi, Ducati, Yamaha, and others.