valve cover gaskets....

Don't forget to check the PVC hose itself. They can collapse or plug up and the crankcase will pressurize itself and blow oil out the valve covers, crank seals and even out the top of the dipstick tube.
In 1977 I picked up a Dart Broumham for $500 because the owner did not want to spend the money to 'reseal the motor.
For 10 bucks I cured the leaks!!