its more than likely that the gasket/seal is dry... you might as well change it... gasket is like $20, to get the head machined and pressure tested is like $70, rocker cover gasket bout $10, $1 for 600 OR 800 grit sand paper to sand the block.
so for $100 you can get the head done and in good condition. also it is better to do it now rather later when something else screws up becuase of it