One thing I haven't seen discused. Assuming the rear axle is 90* to the vehicle centerline. The axle not being centered in the car shouldn't bother anything. I know my 1/4 panels are slightly different side to side. I adjusted my track bar so that the fender gap is the same on both sides as the tire sidewall clearance is very tight. The axle is now closer to the left frame rail than the right by about 1/4". The car tracks straight, leaves straight, drives straight at the top end.
Doug