Want to Find BFather or Father's Family. Male born 3-15-27

Dad was born 3/15/27. He was adopted by the Kerchner family in Circleville OH. He is the last surviviving member of this family. Three years ago we located his mother Elsie Glassburn (deceased), a sister (deceased), and half-brother. We were so lucky to also find an accepting biological family. (Uncle and several Aunts still alive). Now we would like to find his biological father or father's family. None of Dad's mother's living family know who his bio Dad is. There are rumors that his name was Roby Rainey or Raney. Rumor also has it that his bio dad was married at the time and has other children and that he lived several miles south of Circleville. If you could help my Dad, now almost 76 yrs old, find his bio Dad's family it would be a blessing to him to find the other half of his family.