hi john, i recently went through this and to my suprise the third gear is �15. something plus the vat and the forth gear was just over �18app the dearest part in the rebuild was the head gasket at around �28[which is typical]. for the two gears, 5 gaskets, timing chain, chain guide and stopper lever came in at �170. ive rebuilt a few damaged ktms and this is chicken feed compared.

the �200 ebay may be worth a punt if as kev says the sprocket can be made work. no harm in checking