Head gaskets are about a 1/2 to 1 hour job if there is no silicon to clean off.
The trick is to remove the muffler but only undo the carb at the manifold and push it to one side
Then it is only 4 bolts & the rocker cover comes off then another 8 to 10 bolts & the head comes off
Clean both faces, rotate the engine a couple of times to check the bore then back on with the head, poke in the pushrods, confirm they are seated properly by rotating the engine a few times , set the valve lash replace the rocker cover, carb & muffler and the job is done.
It is always prudent to run the engine for a couple of minutes then change the oil when you have finished.