Steve,
The guy I bought my restored Z1B from was from Cardiff and he used S&T in Bristol (01454 313162), the results are excellent. He also used Marque Restore in Coventry (02476 622225) but was less impressed with the results (he had the items re-done at S&T).
My own personal experience- I used Marque Restore and the results were superb, I guess its a bit of pot luck and at times of high demand (like now in winter) the quality can go adrift- just ensure that they are made aware of the quality you require and that second best won't do and I'm sure you will be fine. From a purely geographical point of view it might be best to use S&T, you could take the parts in from Swansea and it will probably be cheaper than posting with the added benefit of dealing face to face and seeing their set up/ examples of work- good Luck.
