Robin I'd consider an S-10 4x4 unless you are going for a real lowered look. Either stay with the stock transfer case or swap to an AWD transfer case.
The width of the front will be close to the stock truck, meaning you may not need adapters, and you have the added security of 4x4 in those Chicago winters.
You haven't really said what your mpg target is. I get 17 mpg on the highway in my 350TBI powered 3/4-ton pickup with a 700r4. I would expect an S-10 based AD truck to perform about the same using a similar motor maybe a little better because you're lighter, but perhaps not as aerodynamic.
