Do you remember what type of documentation that was provided with the flag you mentioned to confirm it was from the 8th La? The 8th lost two flags during the war, one at Gettysburg and one a Rappahannock Station. The one that was taken at Gburg has seemed to have disappeared from the face of the earth.
I will check the flag at Memorial Hall and look for the number "14" which is on the flag, per the book noted. Also see what they have as documentation and such.
JIM T