Front suspension swap help needed

My son has a 67 Dart. It was a slant 6 drum brake car and we are in the middle of a magnum swap with front discs and an 8.8 disc brake rearend. The K frame is a 67-72. The upper and lower control arms, spindles, tie rods and center link are out of a 76. Steering gear box and arm are from the 67. Only thing I don’t have is the idler arm. Do I get one for 68-72 to match the k frame of 73-76 to match the rest?