'66 Formula S Torsion Bars

What is the difference between a formula s and non formula s suspensions? I thought the big difference was a sway bar, springs, and shocks. And they are probably still using pretty much the same spring steel (5350?) that they used back in the day.

At this point any original spring/shock is going to tired. I had .920 bars in my 65 valiant and it rode good stiff but not hard. I wouldn't hesitate to use 1.0 bars if you plan on any sporty style driving.