PURE Motorsport sells Vogtland progressive rate lowering springs for the 123 chassis, as well as most others. They are not a normally stocked part, but they can get them from Germany. They take about 6-8 weeks for delivery, and are $244 shipped to the lower 48. Their website is
http://www.purems.com if you need to get in touch with them.
RE: Body Roll, I find that the most drastic improvement can be had by switching from the stock Bilstein Comforts to the Sports. Huge improvement in vehicle control and cornering, with little sacrifice in ride quality. This is assuming that ALL of your suspention components are in like-new condition. If not, start with a suspension refurb before any performance mods.