Most head gaskets in the 80 series are not replaced. Most will never fail. See
this poll I conducted some time ago regarding the 80's long term reliability. But this is 'mud and we're wildly paranoid and cheap and prone to drama, doing things like worrying about redundant shovels and whether or not maybe we should carry a spare set of rock sliders or whatever. Ignore it, take good care of your cooling system, and don't rev it to 6,000 the second you turn it on.
It is easy to see WHY they fail - this is a MASSIVE inline six, with an aluminum head and a cast block. The difference in expansion rates is relatively high. Still, most never fail.
Your valve cover gasket, however, is basically guaranteed to start leaking at some point.