If you go to this website:
USA People Search - Public Records, Find People
and search for your Dad's name and put in his age and FL, it will show you all the Richard Burnham's that have lived in Florida. The cities at the top of the list are the older addresses and the ones listed at the bottom are where they are now. Then search for his phone number online and call, maybe you will find him. By process of elimination, you should be able to locate him. Good Luck to you and God Bless!