Kool Sonoma, I'd stick to the 245/60-15 on the front and the 255/60-15 on the rear. The 235/70-15 will look to tall and may hit the fenders around corners. The sidewall hight is almost 1.5 inches taller.
The 255/60-15 and the 245/60-15 are close the same diameters as your stock tires 205/75-15 on them now and your ABS will not run in to any problems as all the tires are within 3% rotation ratio to one another. Optional size I'd get would be the 235/60-15 on the rear, 215/65-15 on the front to give it that old school SS look or go with the all 235/60-15 or 215/65-15 all the way around so you can rotate the wheels from front to back.
http://www.1010tires.com/TireSizeCalculator.asp?action=submit
Most larger tire shops will have different used tire size for you to try on your rims to do a test fit when your ready to buy the tires. Log on to
http://www.tirerack.com/tires/index.jsp and see what type of tires are out on the market and average price.