I will add a bit of new information I have come across. An 1860 census indicates that George W and Nancy were in Mt. Vernon, Lawrence Co., MO, and confirms that their children included Jane, George, and Augustus H. An 1870 census from Benton Arkansas shows Jane age 19, George age 17, Augustus H. age 12, John age 3, and Robert 6 1/2 months. It appears that the family moved following the Civil War.
I would guess that the 1876 land purchase in Arkansas was by George W. junior.