Kzinge - Since the car has a lighter front, let's take this relationship a bit further. Reducing mass (weight) on one end of the car has the same effect as increasing spring rate. Also, street tires and particularly unpaved roads are better suited to softer spring. Let me give an example in the other direction.

My car was using 200 #/in t-bars and a 1.125 sway bar which were working reasonably well in autocross on A008 tires. After installing a set of R1 tires, traction increased but the car rolled much more. Stickyier tires needed more roll resistance (or less weight, lower cg and roll centers). But if we put the super stiff setup on loose surface or even a normal dirty road with street tires and it might skate instead of bite.

That said, to pinpoint exactly the right t-bar for any vehicle requires much more specific information. Shifting as little as 50 pounds from the front the rear can effect the balance when driving. Also, on a B-body, my recollection is that the t-bars are longer than an A-body. Therefore a 1.03" B-body spring is softer than a 1.03" A-body t-bar (about 200 #/in). I*think* you will be in the ball park with anything in the 1" range. Yes, it worth discussing with the venders. And the business about ride height has to do with hex offsets.

If you want to baseline your car, my suggestion is to start collecting information. When you get the XHDs, measure the rate and free arches. When you remove the SS springs, measure them too. Next time the opporunity comes, weigh the car and if you can weigh the front. When you do, note how much fuel and other material is in the car (100 lbs of tools?) and its best if you sit in it. There's a page on my website discussing neutral line and how I applied it to my car but that is probably a step more than most people want to do or than makes sense on street car.

Dangina - As far as just trying the rear sway bar, if you put the car into a tree or telephone pole sideways, you may not get a chance to just take it off. That's what Rick E, FrankenDuster and the rest of us are at pains to point out. You need to sneak up on the rear roll from the safe side, especially on a street car. Please read what Rick wrote about oversteer and speed in that other thread.