Open motors were already on a 2" pipe as were the crates. The difference for 2024 is the crates get a 2.25" pipe and both get a shorty header. If IMCA will let you, Schoenfeld can put a mopar flange on the same spec header the chevy uses. Your definitely going to want the shorty over the cast iron manifold. They are lighter, cheaper and make more power. If you use your 7 1/4 (I still think that is a bad idea when you are allowed a 9" floater) with 4.11 gears and run your 904 in second gear if you have a 1.45 second gear that will give you a final of 5.96:1. That's still a little tall even with short tires, but a lot closer than 4.11 and with out spending any money.