Medium/Large Dog Wanted

Hello! Do you know of a nice dog needing a new home? I am looking for a nice companion dog for my senior dad. He has had several large breed dogs over the years and, after the passing of his latest long-time furry friend, he is ready to welcome another one into his home. My dad is very active outdoors in his yard and garden has a lovely fenced acreage where dogs can follow him around freely. His canine friends are welcome in the house and on most car rides!
We are looking for a mature, calm natured and loyal companion that will settle in to a nice life with my dad. We are not interested in an escape artist or a hyper-active nature. ;)
If someone knows of a dog needing a wonderful new home please let me know. Thank you for considering.