I don't specifically know the answer, but I can suggest to you how you can arrive at the answer. When sizing new wheels, I use this site:
offset calculator. You can put in your stock (or current) wheel width and offset, and then start playing with new widths/offsets, and the calculator will tell you how much space you lose or gain on the inside as well as the outside - in millimeters. Armed with this information, go to your current wheel, and start measuring. See if you will hit anything on the suspension side (remember that the wheel rotates, so check all areas for clearance, not just the obvious ones), or if you will contact the wheel fender on the outside.
Once you have a good idea of the size you think you think you want, post up asking if anyone runs that size wheel (your original question is a little too open/vague I think). People will either tell you they run it with no problems or there are fitment issues. Once you know the wheel will fit, then last step is to find the appropriate size tire to fit that wheel. And you should be good to go.
Edit: having said all that, I know for a fact that people run 10" wide wheels in the back with no trouble. Try checking out American Muscle and Late Model Restoration and shop for 10" wide rear wheels - then look at the specs. They will list the offset (and backspacing). You can use this info to hone in on what you want for the calculator.