I tried to track down the units that may have been involved by using the "Civil War Soldiers & Salilors" database. Unfortunately it wasn't conclusive. Several of the names listed show multiple possible matches. Several are inconclusive. Busbey doesn't show up at all.
The only good match I found was for Capt Geo (George) Carter. He is listed as a member of the 4th Regiment (Murray's) Calvery. I found this information regarding Capt Carter: "CAPTAINS-George W. Carter, Co. "A". Organized June 14, 1862 at Chattanooga, Hamilton County. Became 2nd Co. "D", 1st Confederate Cavalry; later an independent company; in 1864 consolidated with 1st Co. "A", 13th Tennessee Cavalry". This unit defended the near by Saltville salt works in October of 1863.
Several other fairly good matches are for the 63rd Regiment (Fain's) Infantry. This unit was attatched to Longstreet's Corp in late 1863 and then moved from Bristol to Petersburg in May of 1864.
Well, so much for my speculation. Anyone with some solid information?