Oh well, it was always going to be a project, it’s just a slightly bigger project than I expected. Hejira Racing have a website, maybe they know something about it. Thanks for the info.
The tank is ally fabricated job, apparently new but don’t know where from. Unfortunately the bike had been slapped together to sit in a museum. It’s a very long way from rideable and will need building more or less from scratch. But all of the bits are there, or thereabouts.