You assumed correctly George. The NGL said what they said because of the In Memory Stone you generated when you created the In Memory of Stone.
Although I have not read Ron's book I would tend to think he did an accurate and great job.
I did find Company F of the 7th Mississippi Infantry movements in which Ron probably also noted. This is what it said. "Formed line of battle on the east bank of the Chickamauga Creek on September 19th and then crossed over the creek. Battle then raging and held in reserve till the morning of September 20th then moved on the enemy and fought all day. On the 21st moved to within eight miles of Chattanooga on the Chickamauga Creek, remained there until the morning of the 23rd"
One idea might be to find others who were in the 7th Regiment Mississippi Infantry who may have also been killed on September 20, 1863 at the Battle of Chickamauga to see where they may have been buried.
I have Grady Howell's reference book "Mississippi Brass" and it would list who the surgeon was with the 7th Mississippi Infantry. And or you might get lucky looking at the Confederate Veteran Magazine to find first hand accounts of the Battle.