Reducing body roll. SS springs, sway bar, or both?

One clarification: NEVER install a rear sway bar if you don't have a front sway bar. I say this because the OP didn't specify, and his problem was with roll in the rear.
And you want a bigger bar in the front than the rear. I'd also use some stiffer torsion bars. As for the rear springs, check with options from ESPO and General Spring. You want something for the street that doesn't raise the rear up like a stinkbug. They handle terrible that way. Forget the air shocks too.