The 94-01 Integra springs will not fit the 1990-93 model years.
The difference in weight is negligible. While the 90-93 coupe is marginally lighter, the increase in spring rate is not going to dramatically affect body roll.

An aftermarket sway bar set will yield the most dramatic improvement. If you can no longer find aftermarket sway bars, the next best thing is a shock and spring upgrade. I'm not a big fan of coilover sleeves, personally... but a Bilstein HD / H&R Sport combo will do nicely.