Tires rubbing

Right, and if one of the rear springs is high then the opposite front corner is low.

He already knows he has cheap jegs wheels on it, more than likely they're 0 offset which isn't right for an A-body. If you hear hooves, you should think horses not zebras. Unless maybe you're in the Sahara.

The wrong offset wheels can cause his exact issue. Body tolerances on these cars were over a 1/4" from the factory. Tires on opposite corners rubbing because the wheels have the wrong offset is par for the course.
Whatever.....