The Tokico springs would be the first thing to change so you don't end up bouncing down the highway with stiffer springs. Stiffer shocks first will allow you to try stiffer springs. I put on Bilstein rears and Tokico front shocks this year and they match pretty good with Voigtland 1" lowering springs installed at the same time. The 2" lowering springs are heavier and may not match as well. The shocks should handle used sport springs fine.
1992 Tbird LX 5.0, 3.73 gears, 1995 Cobra intake, deleted air silencer, 2.5" mandrel bent dual exhaust, SCP shorty headers. Updated four-hole fuel injectors. SK shift kit in AOD. Vogtland 0.9" springs, Tokico and Bilstein shocks.