I"m sure you know that Claude's Buggies is now CB Performance, and they should have any parts you need. Their Dellorto book is probably the most complete and best reference around (
http://cbperformance.com/catalog.asp?ProductID=2), and at only twelve bucks or so a deal at twice the price.
Also John Connolly at www.aircooled.net is an excellent resource, check out the "tech reference" part of his website for some 'how to sync dual carburetors' instructions and other tech articles that are pretty evolved and user tested for understandability. John uses what he sells and is also good with his neighbor Art Thraen of ACE, the ultimate Dellorto specialist. Art has repeatedly salvaged carbs with frozen throttle shafts that I would have otherwise tossed, and might be able to dredge up parts that you otherwise wouldn't be able to find.