[Rude Dude]

I would think the length of the bars or radius rods would determine placement of the brackets forward of the axel. If it were me I would center the rear axel in notch were the axel is suppose at correct wheelbase measurement at ride height. Next use a square tube and temp weld axle to frame solid at ride height to hold it centered in frame, next determine bag or spring mount. Measure evenly and diagonally for forward placement of forward mounts remembering to keep everything at ride height and decide if diagonal stock frame supports need trimming.