You can use springs from a '78-'85 Malibu or Monte Carlo V8. Springs from a 4.3 V6 S10 will work, too, seen plenty of V8 S 10s riding on stock springs without any problems.
Also, to get a better ride (especially if you run drop springs), you can use shocks from the malibu on an S10. They're direct bolt ins, just don't need to use the mounting studs for the lower in the rear.
