Thanks Ped - nice summary of the bass (currently) and its history + some nice photos - hopefully, this might find a new owner whilst I'm away: would have been a nice & unique fiver to keep, but not possible.
I'll try to find photos of the original bass and post them asap.
Should add, for those that might wonder, that the original idea was to replace the broken truss-rod, but the thru-neck was also warped and the only remedy was to replace with a bolt-on. There was a lot of work to be done: the original finish was tricky to remove/balance and the neck re-fit involved a lot of additional/one-off routing (including accomodating the J-pickup into the extended Marleaux neck) - I think the photos reveal what an excellent job they made of this!
Some specs: 34.5" scale (with zero-fret), 1.75" Nut, string spacing is 9mm (Nut), 16mm (24th fret) & 19mm (bridge). I forgot to note the weight but recall that it's very light at 8.25 - 8.5 lbs.