Here's a thought... could the chassis be twisted?
If you can, put the car up on 4 jack stands. Set the height of the fronts to the same side too side and use same pick up point. At the rear do the same thing, same height side to side and same pick up point. If it is sitting square on all 4 jack stands, start measuring
suspension mounting points to floor. If any great discrepancy you may start getting an idea what could be wrong. One possibility is that when the subframe connectors were installed (assuming welded in connectors), if chassis was not square a twist could have been induced.
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