68 Charger steering issue

We recently received a car from another shop that had a whole list of problems. All were already paid to be fixed unfortunately. One of the issues is steering. The other shop installed a new steering box, but the steering is awful, I don't think they even drove it, mainly because the brakes barely work even though it has a new disc conversion. The steering is what I would call extremely loose. You can turn it left or right then bring it quickly back to center before it actually starts to turn. It's so bad you can almost get out of control around 30 mph. It has a new box and looks like suspension parts have been replaced within the last few years. I called the company that sold the box, Classic Industries, and they have no clue. Any ideas?