It all depends on which Super Stock springs you buy. For the A body, the 3000 lb SS springs are nearly identical to the stock '69 GTS HD springs that it came from the factory with.
It does depend on which ones you get as the spring rate varies, but just because they look similar doesn't mean they are. They don't have the same number of leafs on the left and right springs, and Super Stock springs start at around 140 lb/in for a spring rate, even on the ones for the lightest weight cars. That's still too stiff for a street car. I run 120 lb/in springs on my Duster, and it's pretty well balance with the 300 lb/in 1.12" bars I have up front.