You're right about the HEAD and HORNE family not connecting with the 9th GA Inf, but the Roster of Confederate Soldiers, 1861-1865, shows:

Kilgore, James GA 9th Inf. Co.C
Kilgore, William GA 9th Inf. (St.Guards) Co.F

Kilgore, James GA 16th Inf. Co.F Sgt.
Kilgore, James GA 40th Inf. Co.G

Head, Joseph GA 24th Inf. Co.I
Kilgore, William GA 24th Inf.Co.H