It's pretty simple. Loosen the two bottom head cover bolts, but leave them in the cover (no room to fully remove them). Take out the other bolts, and lift the head cover out vertically. When removed, you can work on the t.stat cover on the workbench. The '84 has a couple of bolts at the bottom of the t.stat cover, and that's an improvement over earlier models (lower left side tended to leak, in my experience). I would resurface both the t.stat cover and the head cover before reinstalling. Use a piece of wet/dry sandpaper on a flat surface, and move the mating surfaces in a figure eight motion until you get a uniform shine.
Need new head gasket and t.stat gasket.
[edit., probably a good idea to resurface both mating surfaces for the t.stat cover -- cover and the t.stat side of the head cover.]