Torsion bars for better handling; your experience?
1.03's or 1.06's. Unless maybe you're planning on autoX or road courses, then bigger. The 1.03's from PST are less expensive and you can get a FABO discount if you call to order, they have a good wheel rate for the street. Toss the KYB's in the trash, they're terrible for large torsion bars. Bilstein rcd's or hotchkis fox's for shocks. I've heard the Viking adjustables work well too but I haven't run those myself.
20:1 would be a good compromise for the steering, and will make it easier to deal with running more positive caster. I run a 16:1 manual box and still manage to handle the 275/35/18's I run, I've run those with as much as +8* of caster (briefly). I ran +7* for a decent stretch although currently I'm running +6.25* for caster. I may go back up a little on the caster though, 6.5* or maybe just under 7. A little makes a big difference actually, the difference between +7* and 6.25 was pretty significant for steering effort. Still probably not something you'd want to parallel park everyday though.
I haven't posted my set-up on my Duster in this thread although I've posted it a bunch. 74 Duster (Demon tribute), 340, 4 speed, B body 8 3/4-
1.12" torsion bars from Firm Feel
SPC adjustable UCA's from Bergman Autocraft
QA1 tubular LCA's with custom gussets
Delrin LCA bushings (Bergman Autocraft)
Adjustable strut rods
Hellwig 1-1/8" tubular front sway bar
Hellwig 7/8" rear sway bar (e-body)
Hotchkis non-adjustable fox shocks
AFCO 120 lb/in rear springs
1/2" spring offset w/ spring sliders
16:1 flaming river manual steering box
275/35/18 tires on 18x9's up front
295/35/18's on 18x10's out back
I've also run the car with 1" Just Suspension torsion bars (too soft for me) and 11.75" disks. The 11.75" disks work great but I run Dr diff's 13" cobra style set up now with the 18" wheels. I had bilstein's on it as well for awhile with the 1.12" bars, they work well but the hotchkis shocks handle the 1.12's just a little bit better. It's a small difference but with the 1.12" bars the hotchkis shocks are slightly better. I still have bilsteins and 11.75" disks on my Challenger, it's a good set up but my Duster is set up a little more aggressively for handling. Still my daily driver though.