Dave, in the early 90s Paul Giles raced his Cheney XL in pre '75 here in NSW with no problems. I've got a '74 Cycle Guide (or Cycle) magazine with a test of the bike. According to the magazine testers, the bike performed pretty well until the Gas Girling shocks went off...on the third lap. With far better shocks available today I reckon it wouldn't be the problem it once was.
Pauls son Shawn will eventually bring the bike out of hibernation for some skids, probably at a CD style event.