I have found Cornelius Miller in 1870. His father, head of household, is listed as "Aop Miller," someone's lousy reading of lousy handwriting for "A. J. Miller."
Cornelius is listed as 8 years old, despite being past his birthday when the enumeration was made. I'm beginning to suspect that he was actually born in 1862, not 1861. It is hard for me to figure how an error of a year in his age could have been made when he was so young, 8 in 1870, 18 in 1880, having had his birthday already in each of those years. Maybe people just didn't care.
Anyhow, the big news is that he did not live on Hungart's ("Hungard" on official maps, its seems) Creek in 1870. He was enumerated in the Blue Sulphur Township of Greenbrier County, post office: Lewisburg. I don't know exactly where this is, but Blue Sulphur Springs and Lewisburg itself are 12-20 miles north and northeast of Talcott.
Talcott was not used as the name of the community before Big Bend Tunnel was bored. The post office there was first called "Rollinsburg," and it was on the opposite side of the Greenbrier River from Talcott.
Anyhow, Cornelius Miller did not move to Talcott in 1869, as he claimed, since in 1870 he was still living at some distance away.
To me, the best interpretation is that the family moved to Talcott ca 1879, when Cornelius was, as he said, about 17, some 7 years or so after Big Bend Tunnel had been completed.