Don't stop at the freeze plug...keep going. Put a PCV somewhere on your valve cover. You've got to vent that crankcase or you will have oil spewing out of your dipstick. If you have the older type engine with the oil filler tube at the front of the engine and no holes in the valve covers, change the valve covers to the newer type. Put in a PCV valve in the valve cover and run it to the air filter or to the carb. Use a breather type cap on the oil filler tube. Fresh air will be pulled through the breather cap, through the crankcase, and down the carb, relieving the crankcase pressure.