408 stroker header size

Hi there I recently bought a 408 stroker with a 727 transmission with a 2800 stall. The motor made 418 hp to the rear wheels in the previous owner car with shorty headers but he said it was choking it up a bit. I'm putting this engine in my 1971 Plymouth duster with power steering, it currently has 3.55 rear gears in it. What size headers do you guys recommend It looks like only dougs or tti fit my car. Should I go with the tti stepped header or the 1 7/8 headers? the car is going to be a street strip car and I may spray like a 100hp shot occasionally.