Tom, I'm truly sorry for the loss of your dad. I hadn't realized how difficult that can be, until my dad passed away in 2007. There were all those mixed feelings of loss, regret, and just emptiness in part of moy own mind. It looks as though you too have great memories though of good times and lasting knowledge and wisdom received, and I'm sure he know all that when he moved on. It does get easier with time. Best wishes.
SK