340 - Stock Exhaust Manifolds or Headers

I finally purchased a numbers matching 1972 Dodge Demon 340 4 speed assembled on 10/25/1971 with a rebuilt 340 engine to 69/70 Dodge Dart specs. The only thing I plan
to add is a set of TTI Headers. Since the 340 is basically stock with six pack cam 280 D 474 lift. Should I follow TTI s advice and run the 1 5/8 primary to 1 3/4 secondary
headers or can I install the 1 7/8 inch headers being that the Demon is a standard.