Just get the 97 to 04 k5 clamps ,they should bolt straight on they didnt change the frame, heaps of forks fit these , they even bolt on kdx 200 h series . There even a company in australia ez3 that will make any clamp with any off set you like , we have a set on a kx450 19 which has a set of kx450 14 air fork on it while we wait for a fork part to arrive , even a 97 kx250 front end slides straight in to 19 to 21 kx450 clamps , when you do it you need the forks and front wheel makes things easier, some models clamps like kx250 97 onwards have different length stems and bigger top bearings so stay away from them .but they can be made to fit.Summary get the 97 to 04 k5 clamps and fit kx450 forks and wheel 13 and onward and i say some of the earlier ones might go straight on as well , but you still need to check spring rate and change the valving to suit the k5 90 model rear shock or you could end up with a unbalanced bike.