Sway-a-Way recently also started making larger-diameter torsion bars for classic Mopars including A-bodies. Just another option to consider, they have diameters from 0.96" all the way up to 1.24" which is the max you can go due to the size of the hex at the ends. Their site also includes a handy chart showing spring rates.
MOPAR Torsion Bars - Sway-A-Way | Racing Technology