I have a 1967 ford Galaxie 500 with a 390 engine. I have white smoking coming out of the tail pipe. I notice?

on #8 cyclinder the push rod is bent and the spark plug has oil in it. How much is that going to cost for repair and how do I prevent that from happening again. The oil is not milky and i have all my coolant in the radiator. Atleast I know I didn't blow a head gasket. I also have change out the modulator valve on the transmission since I was having problems going into 3rd gear. That is working perfectly. When I bought the car the car wasn't running. I have finally got it running recently. After replacing the battery, spark plugs, starter solenoid, pick up on the MSD distriubutor and also replace the coil, and replace the heater core. Doing small jobs like I have done I feel comfortable doing but replacing a push rod is that difficult to do or should I take it to a experice mechanic that knows how to work on a older engine.