Knock and smoke
You should drain the oil pan completely and get all the water out of the bottom end. You don't want it to start rusting. I would probably go get 2 gallons of Cheap oil and fill it back up. Put 1 Gallon on each side all over the Rocker assembly and let it drip down into the pan on both sides of the engine.
When the heads were installed did you make sure the surfaces were flat "resurfaced" and clean before installing them?