I built a hemi dart years ago using the hooker 2-1/4 primary tube 4 inch collector original style headers. I did it the factory way. clearances shock tower, moved master cylinder on flex lines, cut down steering column outer tube, spaced K member down, elongated holes on steering box and moved it over, etc. even then i still had to have some header tubes modified to fit.

If i had to do over again I would use a motor plate, and have headers custom built. Put the motor in a place where valve covers come off, might still have to do offset master cylinder and some shock clearance work. But moving steering box and stacking k member, i wouldn't do that ever again. I built the car around the headers, next time build headers around the car.