Hi Jim,
Well, at least you got a response. They never replied to any of my emails. From Glenn Dedmondt's book: THE FLAGS OF CIVIL WAR NORTH CAROLINA, overall flag: 72"x 137", the canton: 36" x 56", red cross: 5", white fimbriation: 2.5". I would take that last measurement with a grain of salt as from the photo you can see the edging looks more like 3.5" to 4" wide. I don't believe Glenn had access to the actual flag and was probably fed those measurements by the museum.
Cheers