[KiltedBanshees93GT]

I cant say as far as the wobble goes, but I know the early stangs are notorious for the loosness of the steering. Mine does the same thing. Its due to the design of the steering box which used a worm gear instead of the more modern rack and pinion. Basically, the design allows more "play".
Your 2 best options are to either go with a rack and pinion install ($$$$ but nice from what I hear) or there are a couple of companys out there that make updated steering boxes, flaming river is the first to mind. Its about $500 but helps tighten the steering up a good bit, but not as much as a rack and pinion setup.
I'm thinking about the flaming river box myself. This is also assuming that your box is in good shape. If its trashed bad enough, just getting a new stock box might be all you need. It depends on the level of performance youre looking for.
J