Torsion Bar Upgrade for '65 Barracuda Formula S
I'd go 1.03" and never look back. With radial tires you still wouldn't be oversprung. A 1.03" torsion bar on an A-body works out to about a 215 lb/in wheel rate. Which is in the ballpark for most modern econo-boxes, and lower than most performance oriented cars.
A good set of shocks would be great addition, but as long as you don't use KYB's you'd probably be fine. I ran 1" bars on my Duster with those regular old replacement blue monroe's and it was still quite a soft ride.