While I can't help with the rebuild kit I would like to reiterate how important changing the fluid is, especially the clutch fluid but brakes as well regularly.
Bikes I see failures on are almost universally ones where the fluid seems to have been changed rarely, if ever.
A case in point is my Green Shitter. The previous owner may of spent a fortune on horrible exhausts and power commanders followed by, when the PC died, money for a truly awful attempt at a map but he never spent money on brake fluid! When Michael was going through the hydraulics the fluid reservoirs looked like a meth lab! It's a 2010 and it never looked like it had been changed! The result of this is that the clutch master is buggered. It still works, to a point, but it does that thing of if you feather it in traffic the fluid leaks past the primary seal so even if you pull the lever to the bar the clutch still drags sufficiently to prevent shifting into neutral and unless you remember to fully stroke the piston prior to releasing there will be a leak point where the clutch automatically disengages! It doesn't happen often, but when it does it's more than a little disconcerting!
All of that could of been avoided just by changing the fluid once a year! Now I have to shout it a new Master Cylinder which is boring and expensive!