If you're in the 'States, I'd try references form WERA and AHRMA. Possibly someone at the AMA or VJMC. There are a couple of people, inluding Claude, who make frames and ride HP rigs (high powered) at
www.sidecar.com Also, there are several SC related groups at Yahoo Groups and one may have advice on racing rigs. Also, Google "Dawg Poung Racing"- they have a rig at the IOM right now I think. They're based in the SF Bay Area and the rig they have is Triumph. Long-shot, but they might have some connections. Cool pix at the site, anyway.
Please post what you find.