Fantastic, thank you very much for your answers.
I would like the bike to be as original as possible without going OTT, so the front end will go and be replaced with the proper one, the rear end looks original, cable brake etc. I think that the twin carb head will have to be replaced with a single carb head, I don't have the manifolds for it and I have a feeling it might not be the head that came with the bike originally anyway.
I believe the bike was being raced at Crimmond before it was taken out of use, hense the later front end and the twin carb head.
If anyone has a single carb head from 1956 or would like any of the spare bits I have, please get in touch ;-)))