First off, never run your engine with an overfilled crankcase, an overfilled crankcase will expose the oil to the spinning crank thus causing the oil to faom, oil pressure to drop and subsequent engine damage.
Second, the PCV (positive crankcase ventilation) system relies on engine vacuum from a vacuum port below the throttle body/carb, inside the valve cover lies a sheetmetal baffle preventing oil from being drawn into the intake system, it is normal to see a little oil seepage at the PCV valve grommet, if there is excessive leakage it would not be caused by an overfilled crankcase, check the grommet for pliability,if the grommet has hardened from the exposure to heat and oil over time,replace it.