It should say, "I'm TRYING to do a heads gasket repair".. lol
Get the manual FIRST.. or your next thread will read, "MY 650 wont start after HG repair"..
Sorry but I'm no help w/ the manual..
Take the rocker arm assy. off as a unit.. leave the adj. alone for now.. just take the whole rack off & set it aside..
THAT WAY, you'll atleast be close..
Check the push rods for straightness.. easy way is to roll them across a counter top..
Leave the thermostat OUT on first start up & use WATER.. THAT WAY, if somethings wrong you didn't waste any money..
Get the radiator replaced or CHECKED.. most HG repairs are do to overheating.. you probably don't wanna do it twice..??
Good luck w/ the repair & let us know how it went..