Great story. Don't give up. My story is the opposite of most, I was searching for the original owner of my 68 Z28, instead of looking for a long lost car. But, even though I live in RI, and the car was originally purchased from a dealership in Tennessee,...I did eventually find and get in touch with the original owner, and was able to get a few pictures from him of the car when brand new.
I think, regarding your hesitancy if you do find him, if you get his address, just send a letter to him. Yes, the old snail mail, it's less threatening than a knock at the door, and less likely to never be seen, like if you send him an email and it goes to his spam folder. A letter explaining your story, with a couple of copies of pictures of the car from back when your father owned it, would definitely ease the fear he might have.