Questions about torsion bars?

I don't understand why Firm Feel lists a set of their 1.00" torsion bars for $339.00 and PST has a set of 1.03" bars for $239.00. Is there a big difference in quality? Or should I go with a set of mopar performance .990" or 1.040" bars didn't check prices on them yet. The car is a real 67 383 Dart, 4 speed, manual steering 16:1 ratio firm feel box and has 6 leaf springs in the back. I want the car to handle good but not pound me to death when driving. Maybe I will eventually upgrade upper and lower control arms at some point and I will be switching from kyb's to bilstein's or fox shocks.

Carl
Quality, supplier , forger , brand etc. 1.03 bars would do you fine along with a set of bielstien shocks.