Steve,
I'm so sorry to hear about your Dad. Only he can decide what he wants to do but at his age I would be concerned about his ability to withstand the surgery. My Dad was 79 without any other health problems when he had surgery for salivary gland cancer and never did recover from that. He was unable to swallow or talk and consequently passed away in 5 months. I wish he would have tried the radiation first to shrink the tumor but the Dr. insisted that surgery was the best chance for survival. I pray that God will help you make the correct decision and give you and your family strength to get through this. God Bless :-)