Dawn

I replied to your PM on salvage surgery but after talking with my wife, I wanted to post here also. She reminded me how her beloved grandmother had aggressive surgery for her heart and a pacemaker when she was 81 which let her live until 98. But those extra 17 years caused her nothing but sorrow.
I'm with EricS on this one. No doctor really explained the day to day complications and trials that result from surgery, in my case because they were afraid I'd just fly off to Amsterdam for death with dignity (Oregon has a one year waiting period and all the doctors said without the surgery, I'd have less than that) My grandmother in law had that surgery because she felt her children and grandchildren expected it, and it's true they did not want her to die. However she lived to regret it.
Your dad is already on a feeding tube, surgery or radiation or chemo is not going to get him off one, instead they will make it permanent just like mine. This has to be your dad's decision and while you are an amazing daughter, willing to move cross county to tend to your dad, he deserves to know all the gory details so he can make a choice that works for him. As I PMed you, all the doctors tell me its unrealistic for me to expect to live until 85 but I don't think I'd do it again at that age. I needed to see my son graduate from college and enter law school, so salvage surgery made sense for me. There was a good chance I would not even survive my surgery (8 hours and an ENT surgeon and plastic surgeon taking turns)and I'm 22 years younger than your dad and was in excellent physical shape.
Finally here are two links to what I feel are good articles. they may raise more questions than they answer, but as you say, you are trying to gather information
Treating Recurrence
Toughest time in battling cancer
Again, you are a wonderful daughter and caregiver. Your dad must be very proud of the way he raised you. My prayers are with you at this terrible, terrible time
Charm