The various wear and/or damage prone parts are better being renewed in unison along with the other components that make up the crank/piston assembly including connecting rods, piston, piston rings, piston pin and the piston pin retention circlips not forgetting those all important bearings - all pretty much essential when rebuilding the engine.
Interfacing new parts with old will cause the new parts to wear prematurely and lead to a less than satisfactory outcome.
Other related parts you may wish to consider:
Choosing the correct specification gaskets & seals will give the best results; improve the results still further by using this pro-workshop gasket sealant: 08C70K0234M.
Add as many components as you wish to the same shopping cart, new bolts for example, and still only pay the same single fixed price shipping cost.
This component may have other applications within the Kawasaki model range.