interesting one this, the SFC1000 Was originally built with 30 year old (on the shelf) Smiths clocks and had the correct ring gear and worm for those clocks, this was a disaster because the grease in the clocks had hardened and this caused multiple failures and a re-call, the dealers were supplied with a new dash mount and the white Veglia clocks, much more stylish and in keeping than the Smiths, those dealers were also supplied with a replacement ring gear and worm, because different ratios were needed at the front wheel, not many of the bikes that were recalled for this change got the gear ratio changes (lazy blleeding dealers!) this is why most SFC1000's have wildly innacurate speedos.
BE QUICK, Alan Bell (Kelip Kelip on ebay) was advertising some of these Veglia drive kits a few months ago, he might still have some!
he might even see this post, if not PM me and I wil put you in touch.
CLEM