Syd's Cycles in Florida has a lot of stuff, but they aren't the most affordable place in town. Road and Race in Australia also has a lot of stuff and is sometimes cheaper, even with shipping. I've found they are also sometimes faster than Syd's...
But your first stop should be
Ducati Meccanica. Scroll down the page to the suppliers section, there will be contact info for a bunch of places. At the top of the page there is a link to join the Bevelheads mail list. This is where you'll find a group of people interested in bevel Ducatis in general and who can probably help you out with a lot of the issues you'll run into while you restore this thing.
Have fun...