Bars and springs match?

Sorry, I was at work the last couple days so I wasn't on here much.

I think you already figured it out though. KYB's and Bilsteins aren't comparable really. They're both shocks that will fit these cars but that's pretty much where the similarities end. With 1.03" torsion bars I would use the Bilsteins. They'll give you the ride that you're looking for. The KYB's are just harsh, there's no way around it. With larger bars they will straight rattle your teeth out. As I mentioned in that thread you linked, and many more like it, I kick myself for not swapping to the RCD Bilsteins on my Challenger sooner. I spent 10's of thousands of miles abusing my kidney's and fillings thinking it was just the price of large torsion bars and good handling, when the fact of the matter is that a car like my Challenger with 1.12" bars and RCD Bilsteins has a better ride quality than a car with sub-1" bars and KYB's. It's a dramatic difference.

As far as the springs and torsion bars being matched, I think you're in the ballpark. Remember these cars from the factory were seriously undersprung in the front, but in the back the factory spring rates weren't actually that far off. The Mopar Performance handling book gives spring rate recommendations of like 120 to 130 lb/in for handling, and the Mopar oval track springs are 120 lb/in. The stock XHD's are 110 lb/in and that should be pretty close to what the 6 leaf ESPO's are. I run 1.12" torsion bars (300 lb/in) on my Duster with AFCO 121 lb/in leaf springs, and it's a pretty well balanced car. I have a larger, E-body Hellwig adjustable rear sway bar on it so you could run higher rate springs than I do with 1.12's, but I wanted to have the adjustment with the rear sway bar.

1.03's and the ESPO leaf springs should be pretty well matched for your needs. If you add the Hellwig front sway bar, you should add their rear bar as well. You might use it on the lowest setting (it's adjustable and has 3), but I think you'll want to add the rear bar with the front to keep things balanced. With the +1" springs you'll have a higher roll center in the back than in the front.