64 Barracuda torsion bars

I don't think you can go wrong with the 1.03" bars, unless maybe you're looking for some aggressive handling capabilities in which case you can definitely go bigger. That would require better tires as well though. Your '65 is no doubt lighter than my '74 Duster, but I run 1.12" torsion bars AND front and rear sway bars, and I use my car as my daily driver too.

I will say that you should choose your new shocks wisely, and spend a little money on shocks that are intended to work with higher wheel rates like the ones you'll get with the 1.03" torsion bars. The RCD Bilsteins are great shocks for that size torsion bar, and PST sells those too. If you slap a set of KYB's on there you probably won't like the resulting ride quality.