Sway Bar yes or no
All the factory bars are too small, even the ones that came on the 383 cars. You have to keep in mind that the stock torsion bars were sized considering that the car would be running bias ply tires. Even switching to BFG T/A radials on a 15" rim is a massive upgrade in grip compared to what was stock. Then, you can further consider the "style" at the time was for a soft, floaty suspension. Not performance handling but comfort. Throw in shock technology at the time and you end up with a very undersprung suspension. That's not just my opinion, those are the simple facts of how these cars were set up. The wheel rates for the factory suspension compared to the corner weights of these cars are just silly.
Now, in my opinion, even running 15" wheels and BFG T/A's everybody should be running 1" torsion bars or a little bigger unless they're running their car as drag race only. I ran my Duster around for a several months with 1" torsion bars, stock replacement shocks, and 225/60/15's all the way around. And the suspension was still pretty soft for the amount of grip I had. The car needed sway bars at the very least, even just for the 225/60/15's.
Running 17's, sway bars, lowered, tubular control arms, nice shocks, etc I wouldn't even start at 1.03". Especially since you're wanting a "firm correct handling car". I'd be looking at 1.06's (Firm Feel), 1.08's (Bergman or Sway Away), or even 1.12's like I run (firm feel). I don't think you'd have an issue with the 1.06's at all. And, with bars of that size you could lose the drop spindles and run standard 73+ spindles and lower with the torsion bar adjusters. Which would improve your suspension geometry. You could easily be lower than you are currently with 73+ spindles and 1.06's. To get as low as I am the 1.12's are necessary because of the reduced travel, but my car is quite a bit lower. My flange measurement is also to a set of Doug's headers...
The angle isn't quite right, but the bottom of the flange is a little above 3 3/4". Even a little bit higher than this would work fine with the 1.06" bars and standard spindles, and would be way lower than you are now at 5.5" to the flange.
All the factory bars are too small, even the ones that came on the 383 cars. You have to keep in mind that the stock torsion bars were sized considering that the car would be running bias ply tires. Even switching to BFG T/A radials on a 15" rim is a massive upgrade in grip compared to what was stock. Then, you can further consider the "style" at the time was for a soft, floaty suspension. Not performance handling but comfort. Throw in shock technology at the time and you end up with a very undersprung suspension. That's not just my opinion, those are the simple facts of how these cars were set up. The wheel rates for the factory suspension compared to the corner weights of these cars are just silly.
Now, in my opinion, even running 15" wheels and BFG T/A's everybody should be running 1" torsion bars or a little bigger unless they're running their car as drag race only. I ran my Duster around for a several months with 1" torsion bars, stock replacement shocks, and 225/60/15's all the way around. And the suspension was still pretty soft for the amount of grip I had. The car needed sway bars at the very least, even just for the 225/60/15's.
Running 17's, sway bars, lowered, tubular control arms, nice shocks, etc I wouldn't even start at 1.03". Especially since you're wanting a "firm correct handling car". I'd be looking at 1.06's (Firm Feel), 1.08's (Bergman or Sway Away), or even 1.12's like I run (firm feel). I don't think you'd have an issue with the 1.06's at all. And, with bars of that size you could lose the drop spindles and run standard 73+ spindles and lower with the torsion bar adjusters. Which would improve your suspension geometry. You could easily be lower than you are currently with 73+ spindles and 1.06's. To get as low as I am the 1.12's are necessary because of the reduced travel, but my car is quite a bit lower. My flange measurement is also to a set of Doug's headers...
The angle isn't quite right, but the bottom of the flange is a little above 3 3/4". Even a little bit higher than this would work fine with the 1.06" bars and standard spindles, and would be way lower than you are now at 5.5" to the flange.
