Kritter,
There are several guys in the A.F. Thread that I'm sure you will want to check out,
the Aluminum Frame Gang have posted up pic's and how to's, and what to look out for's.
http://www.kxriders.com/forums/index.php/board,24.0.html The price of the stuff for sale locally can be checked out for a going rate on e-bay.
I would caution you there have been quite a few of us who got bikes with engines that were
"Freshly Re-built", "New Top End" "LO Hours on re-build" and ended up pretty much having to go through the whole engine again.
You may consider setting a side a little over $100.00 (gaskets and consumables) to go through the engine your self, so you Know what you've got. Then you can make an assessment as to what you might or might not need to Replace, Repair or continue to Run.
Tuck\o/
Tuck\o/