Gus McRae was inspired bt the real Charles Goodnight--a Christian, BTW

From Wikipedia:

Following the war, he became involved in the herding of feral Texas Longhorn cattle northward from West Texas to railroads. This "making the gather" was a near state-wide round-up of cattle that had roamed free during the four long years of war. In 1866, he and Oliver Loving drove their first herd of cattle northward along what would become known as the Goodnight-Loving Trail. Goodnight invented the chuckwagon, which was first used on the initial cattle drive. Upon arriving in New Mexico, they formed a partnership with New Mexico cattleman John Chisum for future contracts to supply the United States Army with cattle. After Loving's death, Goodnight and Chisum extended the trail from New Mexico to Colorado, and eventually to Wyoming.

Goodnight and Loving were close friends. Goodnight sat by Loving's bed during the two weeks it took the latter to die, and reportedly kept a photograph of Loving in his pocket long after his death, and later put a photograph on his desk. As requested by the dying Loving, Goodnight carried the body from New Mexico to Weatherford, the seat of Parker County, Texas, for burial.