Lowering the Rear

Ss springs are primarily designed for straight line performance, that's true, but because of the shorter (than a b-body, same as an a-body) stiffer front section, can be made to handle well, with a rear sway bar.
But, if the height has to go, and lowering blocks are out of the question, spring replacement is the obvious solution.
If ride is a concern, go with a standard spring, not an HD. Then add your sway bar.
Edit I'd be curious as to the part #s of your current ss springs. I have 3400lbs ss springs on my car, and it sits at least three inches lower than yours.