Hkr spr comp hedders fit?

Will the hooker super comp 1 3/4 tube small block a body hedders fit on a 75 duster with 360. They say 70-72 only on summits site. What is the real difference other than the motor mounts? I have them on my 73 but running a rack front steer with stock k member. Any input. Planning on installin into the car really soon. Hoping someone has installed them with stock steering. I have manual steering, disc brakes