I am putting a 400 with a 727 in my 70 dart. I have a spool mout k frame and want to use the '73 up style idler, pitman arm and center link. will I need a special steering box or will the early ones work fine? I have heard the pitman arm is different for the manual box from the power units. I have a power box in the car now so I want to buy one that will work. Any one done this before? Any info greatly appreciated.