I've done the swap on a 72,(for a customer).While it wasn't completely custom it wasn't "slap in" either.Used steering box,pump,mount,idler arm etc off a 74 as someone else suggested.The only really custom part was steering column but in able to keep the column collapsable it will take some WORK. I found that on that paticular car it made the steering too light (easy) .Sneeze and you were veering onto the sidewalk.Reminded me of a 67 dodge dart we had but I'll save that for another time. I've had 9 140's and found some steered fine,others were like my driving my 65 ford truck.Often times old,tight ball joints,tie rods,idler arm (rarely) etc.can cause tightness and hard steering.Have you inspected the suspension and steering? Of the 140's I've had only 1 had power steering.a 74 142gl.other than that all the cars have been 68-71 cars.

I want to go rack and pinion.I've heard rumors of 140's running a rack and would love to see some pictures.