I think I’ve found another clue as to where John Pryor and William Pryor (of Sumner and Overton Counties) may have lived in Campbell County, or at least where their Taylor in-laws had lived.
About a decade after the Pryors and the Taylors moved to Tennessee, the heirs to Edmund/Edward Taylors estate sold some land in Campbell County.
Horatio Goff (grantee), from (grantors) M., Hezekiah, Chesley, Spicy PRYOR, Pleasant, Elizabeth, Polly Taylor 11/1838 Book 22 Page 213
I went to the 1840 Census to get a sense of where Mr. Goff was living. He was counted in the North East District of Campbell County. His neighbors’ surnames aren’t anyone I recognize with a connection to the Taylors or the Pryors: Dobins, Thurman, Saunders, Echols, Legrand, Buckley.
I looked again at the 1850 Census. Horatio Goff 66 was counted in Appomattox County (this county was formed out of part of Campbell County in 1845). His neighbors share surnames very familiar to this line of the Pryors: Elbert Legrand 50, Wilson M Wright 46, James D Wright 51, Josiah Woodson 50, Jacob Woodson 85, and several Stratton families (the Taylors married into the Strattons).
This information helps to support that the Pryors and Taylors were from the part of Campbell County that became Appomattox County.