Only little input I can offer up is some kx parts are becoming obsolete. I am currently rebuilding a 125 that needs a power valve - only one side is available and engine needs the other. 200 power valves are available but substantially different-quite a bit taller. Any way just thought I would let you know that parts are starting to dry up.
I know how that is. I bought the last left power valve in Australia for my 87 KX125, problem was I needed both but the right side had sold out long ago...
About the only solution I know of is to have them machined. I remember a guy was having a machine shop make a run for the KDX a while ago out of steel. Or I've seen people epoxy the worn out ones back in, locked in one position they should work alright, if a bit jerryrigged.