That bike looks to be in decent shape, nice score!
Go through the carburetor and pull the top end off to take a look at the piston. If the cylinder walls look fine and there are minimal carbon deposits then just clean it up real good and put a new head gasket on. Make sure it shifts through all the gears. Go through all the nuts and bolts and make sure they are in good shape and torqued correctly (or at least tight). Also make sure the suspension settings are at the very least STOCK. That way the ride wont be a surprise.
This is my regine each time I purchase a bike (own 6 now
)
1) Change the oil
2) Inspect and clean filter (replace if necessary)
3) Go through carb and clean. Set jetty to something that works for you based on the jetting chart on this site.
4) Inspect chain and sprockets for wear and proper tension.
5) Make sure the Controls are in good shape (clutch, break, etc...)
6) Make sure the exhaust chamber is sealed at the head with all the springs and a good copper gasket and new o rings if necessary. Also replay the crunched silencer with a spark arrestor one (unless the bike is race only)
7) Make sure there is good coolant.
Make sure the foot pegs are in good shape
9) Check over the frame for cracks, this is never a bad idea to do regularly.
I always mix my Kawi's 32:1 with a good oil, Like Belray H1R, Klotz or Maxima Castor 927.