It was Clyde Lennon, not Clive.
His 406 bore the registration 4545 WJ and the chassis number was 406/5259
You can do a search of this forum for Clyde's posts or threads using the
Advanced Search function. Clyde's username was 406Special
I've had a quick look myself but I could only find discussions on what "might" be a suitable replacement engine. However I know Clyde ended up doing quite a lot of work on this and decided to use a 2.5L Turbo Volvo engine.
I'm sure I have some detailed information about this somewhere, but I can't locate it at the moment.
The guys at
Alpine Eagle were doing the work on Clyde's car so they might be able to provide some more information. I went along with Clyde to visit Alpine Eagle one day and if I remember rightly they had started preparing the engine bay.