Handling upgrade...what parts?

The alignment is killing you. You've got great parts already. Jim's right on, you need modern alignment specs.

-.5* camber, +3 (or more) caster, 1/16 to 1/8 toe in.

With stock UCA's and offset bushings you should be able to get at least +3 on the caster. I have +5 on my Challenger, but it has Hotchkis UCA's. They're awesome, but I wouldn't run heims on the street again. Stick to a tubular arm with bushed ends for street use. It'll last longer, and with poly bushings you won't give up all that much flex anyway.

Bilstein shocks are amazing. I've heard the Fox shocks from Hotchkis are better, but even with 1.12" torsion bars in my Duster the ride is fantastic. Much better than my Challenger, which also has 1.12" bars but KYB shocks at the moment.

The tires will also help a lot. 245/45/17's shouldn't be a problem at all, a 17x8 with 5.25 to 5.6" backspace will work great. In the rear, with an A body 8 3/4 and an offset shackle kit a 17x9 with ~5" of backspace should work great for a 275/40/17.

I would go up to 1.06" bars in the front. That'll help with your lowered stance as well, as it will reduce the amount of suspension travel needed. The bilsteins will handle those just fine. They'll help improve handling, and will deal with the improved traction better. But the torsion bars aren't the source of your current problems.