You'll have to measure the vehicle to determine the proper offset, since you are running a "custom front suspension" and different rear axle. In two piece wheel sizes which are the most common, you could run 18x8 or 18x9 on the front, and a 18x10 or 19x10 on the back. The 18x9 front might be too much for a stock S10, but with a custom chassis and custom front control arms you should be able to get the extra room you need. If you get into three piece wheels, you can order any width you want, in half inch sizes. Given your ride height and desire for wider track, you may need to do some custom metal work to get the wheels/tires to tuck under the fenders.