Just an FYI, the "special handling" nomenclature means your car was a special build for either an executive of Chrysler, some special show purpose, or as a dealer special of some sort. It actually had nothing to do with the performance potential of the car so much as the "handling" of the order, build, and delivery process.
CP is right in that you generally want to reduce any unsprung weight in your car, which means the car will "feel" the frame hung unit differently. However, for actual performance in a street cruiser you probably won't notice the difference between a frame hung bar and a axle hung bar. Additionally, the axle hung bar will allow you more room over the axle for exhaust routing.
As far as size, that is wholly dependant upon what you have up front, plus leaf spring and torsion bars. If you have a 1" bar up front you probably won't want a 1" bar out back. The reason being that the combined t-bar, leaf spring and sway bars have to have balance. They have to support the weight at their respective ends of the car. So, with the majority of the weight on the nose, you need to have t-bar and s-bar rates significantly higher on that end of the car. If you have super stock leaf springs, you have increased the rear spring rate enough that adding a sway bar may make it feel very light in the rear, especially if you have the stock t-bars and s-bar.
So, in a nut shell, you always go big up front, and small or not at all out back when dealing with predominately stock vehicles.
