Are you sure it was the 6th Louisiana Cavalry? I find a William B. Rourk listed in the 7th Regiment Louisiana Cavalry, Companies A & S, according to his pension application.. This is off his widow's pension application. Please be advised there never were any companies referred to as "S". Rather that probably stands for "Staff" as in "Field and Staff". His application only list Company A. His widow's name was Lydia B. White. The application was filed from East Feliciana Parish.
I did not find him listed in Booth's Record of Louisiana Confederate Soldiers but that may be simply due to a spelling difference. Am I on the right track? If so we can dig a little deeper. Just let us know. Also, let us know if you are interested in just his history or his units history as well.