Carburetor sync is not a big problem, although a lot of folks have spread
rumors to the contrary. Most of the people who spread such rumors just don't
know how the carbs work. It is more important to have the carbs in good shape
(especially the throttle shafts) to get them tuned right because leaky
throttle shaft bushings make the engine run lean at idle but not at speed,
so if you set it to where it idles right it will be too rich at higher speed
and will be less economical.

Haynes publishes a pretty good manual for SU Carbs.
--
George Downs Bartlesville, Heart of the USA!