JK,
Grady Howell's regimental of the 6th has many photos of members of the unit; they are all individual however, there are no known group photos of the unit. My g-g-g grandfather was in Company D, and I have a copy of a letter written by him from Bowling Green that talks about all the men in the unit who died there from disease. If you would like a copy just let me know.
Jeff