I have a 75 that had sloppy steering, it was areal work-out driving around town. I solved that problem by changing out the "rag joint" on the steering shaft. There is a repair kit that is avaiable from a number of catalog companies but I got mine fron Corvette Central.

Check out this link, there are a ton of great tips here. It may help you out
http://www.corvettefaq.com/listing.asp?group=7