Frame out of square

[hammerdog57]

I have a 57 swb frame that i am setting up to do a camaro clip on. I set frame level on jack stands to check frame for straightness and see if it was square. First thing i did was check frame rails with a laser chalkline. rails are within a 1/16" from rear spring mount to factory alignment hole near front axle centerline. I then put bolts in in front factory alignment holes and cross measured to rear factory alignment holes near end of frame. Coming up with a 1/4" difference in measurements. Meaning one rail is 1/8" ahead of the other. Has any one straightened one of these frames? I was planing on using the rear spring mounts with front camaro clip. I dont see any way of squaring the camaro clip to frame rails and still use rear springs. One option would be to square clip to frame rails and use four link squared to frame rails in rear. Any suggestions?