Finally finished after a lot of faffing about with chains and sprokets and tensioners and found a 32 / 18 T, new KMC gold chain plus half link = tada !!!
Have swapped out the battered Syncros post for a nice new carbon version and put my repro decals on.
Never ridden a SS before this and I'm liking it - a lot. It's so quiet, barely makes a sound with the semi slicks on and for round the local roads I can get up most of the short sharp hills without too much trouble. The bike weighs in at 19 1/2 lb and thats with some not so weenie bits like the brakes, pedals and the switchblades aren't the lightest either. Perhaps will see about shaving off another lb in the future but for now I think I'm done