Thank you for your research. I will annotate my text. I mistakenly assumed the William L. Harbin in 1860 was the same as the William who married Emily. He was not. Your man was the one in the Rough and Ready. The other William Harbin (described below) was in the 5th Alabama Cavalry...
The rest of my notes seem to follow the William Harbin who was with the 5th Alabama Cavalry:
Harbin was enumerated on the 1867 Winston County Voter Registration List where he reported he was born in Cherokee County, Georgia on 11 Nov 1824.
The 1870 Winston County Federal Census recorded William Harbin was born in Georgia about 1836; Emley was born in Georgia about 1840.
The 1880 Winston County Federal Census recorded William Harbin was born in Georgia about 1835; Emily was born in Georgia about 1840.
On her Confederate widow’s pension application submitted through Walker County, Emily K. Harbin reported her husband died 3 Mar 1883; she claimed her husband was a Private in Company C of the 5th Alabama Cavalry; application witnesses included W.D. Irwin and M.C. Brown, both of Lawrence County, Alabama; pension was approved.
Monuments in the Rocky Plains Church Cemetery [Winston County] recorded William Harbin was born 11 Nov 1834 and died 3 Mar 1883; Emily K. Harbin was born 22 Jan 1840 and died 6 Dec 1908.
The Cherokee Advance (Cherokee County, Georgia), 7 Apr 1883
Mr. William Harbin was born in this county in 1834 but had been living in Winston County, Alabama for many years. On the 31st ult., while burning off the woods, a dead tree blew down on him and he died in about an hour and a half. He was a steward in the M.E. Church South, a good citizen and loved by his neighbors.
The New Era [Winston County], 12 Dec 1908
Walker News. Mrs. Harbin, the aged mother of Mr. W.N. Harbin, died at her home in Beat 3, Sunday night, after long suffering from a complication of diseases. The remains were carried to the old home in Winston County for burial. A good old mother in Israel is gone to her reward.