Absolutely beautiful! If he ever wants to sell, please contact me directly! My father sold his '66 Formula S when he was young and in his 20's, to a man in Maryland, and he regrets it to this day. It was almost exactly optioned like your fathers: Citron Gold, Formula S package, gold interior, 4 speed, disc brakes, etc.
if you ever come across another one just like this that someone wants to sell, let me know, I'll hook you up with a finders fee if I buy it.