i would like to make some thing clear...
if you are a perfectionist, then to do it right, you will want to drop the motor pull the head.
then replace the head gasket, base gasket, valve cover gaskets, head studs and head bolts.
but most people, including harley would pop the head off, scrap the head gasket off the bottom of the head replace the $4 head gasket.
then clean the valve cover gasket and reuse it, toque the heads and call it a day...
just remember to clean the studs and then use a dab of oil on the head threads and instead of torquing it a 1/4 turn do it 1/2 for the final toque. the head studs are spring rods so used ones are stretched a little.
good luck.