I posted the first message in this thread ages ago and I'm amazed at the response, especially from Mr. Longenecker. My name is also Dave (Chamberlain) and I am a London-based mostly-jazz player. I'm a lifelong fan of Ray, although I never got to meet him in person, sadly.
I spent a lot of time in my younger days transcribing Ray's lines, marvelling at how he was able to produce that devasting sound with Dizzy's big band. (I play some of those charts now with a big band and it's hard to be heard, even with an amp!) I had always suspected that Ray's bass must have been a loud instrument and everything I've read here has confirmed it. I wish I had known of its whereabouts when I was passing through Toronto a couple of years ago for the International Jazz Educators' Conference. I would have LOVED to have tried it out!
Interestingly, there is a London-based luthier called Lawrence Dixon who has been commisioned to build a recreation of that bass to serve as the house bass at Ronnie Scott's Jazz Club. I spoke to Lawrence and he seemed to be of the opinion that Ray's bass was an Amati, although I don't think he has actually seen it first hand.
Does anyone know any more about Ray's second-fiddle (if you'll excuse the pun), the Silvestre? Where does it now live?