I have read that syringa vulgaris (which happily is the most common variety) is by far the best, coming in at 90% specific gravity, and tolerating lots of grain violation ie. ignore the twist. The key is apparently to dry it REEEEAAALLL SLLLOOOWWWW, because it will check within hours of being cut. What I've gathered is that you should peel it, split it to the pith, and wrap it with cling wrap, or paint it with glue. The back will check, and radial checks from the pith will be a problem. Then, after you've tried it out, win or lose, please report back with your findings!
Here's Keenan's buildalong to get you started.
http://www.primitivearcher.com/smf/index.php/topic,4699.0.html