Not sure if Burris was part of the 600, I only posted to this thread so that I would be sure you would get the message. Here is a bit more info for you when you get settled in.
From The CWS&S--
W. B. Burris (First_Last)
Regiment Name 3 Mississippi Cavalry.
Side Confederate
Company B,I
Soldier's Rank_In Private
Soldier's Rank_Out Private
Alternate Name William R./Burris
Notes
Film Number M232 roll 6