Suspension advice

The one part I replaced on my dart that made the biggest difference in the handling was the torsion bars. Went from /6 to .890" 340 bars and it was much better. Then put 1.03" bars in and what a difference they made. I don't feel like they ride too harsh but I have 15" tires on my car. I would say go at least .920" like Joe suggested. Stiffer leaf springs and bilstien shocks would balance the car out well. Mine has a stock '73 sway bar and k-frame with no rear bar and has little body lean on moderately hard cornering.