Suspension upgrades ,the best route
advantages are easier to dial in / tune for autocross
hemidenny kit with coilovers has no bump steer
The "easier to dial in" part gets to be less of an issue everyday. There are at least 2 different, high quality, adjustable shocks available now that are geared strictly to handling. And several non-adjustable shocks that are probably more than adequate for 99% of the street drivers. And the number of larger torsion bar suppliers has doubled in the last 5 or 6 years, there's actually quite a range now available from 1" all the way up to 1.18", with several supplier's offering 1" to 1.06" bars that are great for A-bodies.
As far as "no bump steer", I have news. The original system has very little bump steer. There's no reason to swap out your stock suspension to get rid of bump steer that isn't there. If you had a mustang, different story.
You can check out this article that deals with swapping A-body spindles for the later FMJ spindles. There's a nice table showing the toe-change exhibited by A-bodies, as well as a comparison to what racer's typically look for (less than .031 degrees of change per inch of travel). The table shows that stock cars have MUCH less than that in the positive direction, (.009 per inch!!!) and only that much (.0315 per inch) in the negative direction. Assuming, of course, that you still have 2.25" of travel in each direction, which, if you have 1.12" torsion bars and are lowered like I am, you don't. I might have half that amount of travel. Maybe. So, yeah, I'm not even mildly interested in the amount of bump steer my car has, its less than significant.
http://www.moparmusclemagazine.com/techarticles/suspension/mopp_0503_swapping_a_and_b_disc_brake_spindles/viewall.html