Tim,
Even though not being (at all ...) an expert in mechanical stuff, I can tell you my experience. My replica had the same problem even with the small steering wheel that came initially, the mechanic tightened the screw and the free play almost disappeared, even though the steering was much harder and the steering didn't go to the center after the curve. My mechanic told me this was usually only a temporary solution, since the steering box wears off much quicker when the screw is tightened.
However, since we had a 14" vdm steering wheel to install there, after intalling it, the small free play turned into an inch or more of free play ... felt almost like driving by 'estimate'.
He replaced the steering box recently and it's a huge difference. I brought the car from the upholsterer and drove in high way for 20 miles at 60-80 mph and felt the steering totally safe. I bought the box here because an occasion appeared, but I was going to buy it from www.aircooled.net .
Best regards.
Miguel Caldeira Proenca
Lisboa - Portugal
m.caldeira.proenca@mail.telepac.pt