Design goal for the 7.3L was 400 ft-lb starting at 1500 RPM, and long term durability. There are some torque-speed curves online, and they show a really flat torque curve, with decent gains over the existing 6.2L.
https://jalopnik.com/why-the-ford-super-duty-s-7-3-liter-v8-makes-only-430-h-1836880836“The focus for the 7.3-liter was total capability as delivered in vehicle. We have class-leading peak torque, but we valued capability from 1,500 rpm on up over obtaining an even larger advertised peak torque. All versions of the 7.3-liter are capable of delivering over 400 ft-lbs from 1,500 rpm on up. We believe this large amount of torque from low engine speeds is exactly what a heavily loaded vehicle needs for good drivability.”
