TZR cfl

Hi all im new , was on the off chance wondering if anyone knew anything about this model. I have a parts catalogue buts thats it im needing a piston kit for it as im doing a top end rebuilt but yamaha want £170 for the piston alone then I have to buy rings,circlips etc. I know some of the measurments 56mm piston i think the stroke could be 50.7mm but im not sure. Any information or links to items would be gratfully appreciated.