They would not have had a Hardee pattern battle flag at Arkansas Post as they had not yet joined Hardee's Corps to get one. They probably carried a First National, based on surviving flags and descriptions of flags taken there.
The first time this regiment would have obtained a Hardee flag was after its exchange in the fall of 1863 when it became part of Lidell's/Govan's Brigade of Cleburne's Division. No one wanted these exchanged troops which included the Texans of what would become Granbury's Brigade but Cleburne took them and molded them into tremendous soldiers.
Greg Biggs