If your rear clam is on right (or even if it's not) have a shop align the car, or do it yourself.
The rear swing axles need to be set up near perpendicular to the car's centerline so that each wheel can be set up near parallel to themselves and to the front wheels.
You want a little bit of toe-in back there--like a 16th or maybe an eighth inch. Camber and caster are not adjustable.
On my car there are slotted holes in the spring plate for the bolts that fix the rear hubs. Vintage has a different system to work with the coil-overs—i.e. those big Heim joints—but the concept is the same. Plenty of cars leave their builders without this being done right.
I had mine wrong on first try and the result was noticeable in the wheel arches like yours.
See it? Too far forward, just by a little. The car felt fine but it was "crabbing" down the road.
Much better now.