Yea they are all available. Should be as the quad almost certainly uses the same parts. Very expensive though. I check the condition of the rubber seals and if they are still in good nick I no longer replace them. It has been said that the head bolts stretch and they do, but rather than replace them you can just put washers under the caps. Really if they are not grounding out, I can't see why they shouldn't be ok, but then I'm no great shakes as a mechanic. I would check the pre filter strainer though, it can clog up; oh and use nothing more heavy than a 10-40. I use 0-40 amsoil. The head oiling is dodgy and you need the oil to flow freely through the cam to the journal when cold.
Some markets didn't get the tacho worm drive. If yours has just got a cap bolt, chances are there's no worm drive in the head and there is a plug to be made for resultant empty chamber.
Derail has a thread for this, though personally I can't see the point in taking out the tacho if it is there. Just check all the KLX threads and make your own mind up.