Which torsion bar to use?

Bill Crowell said
I have a '62 Valiant with a Mopar small-block V8 and 8" X 15" wheels that I don't intend to take to the strip at this time. I want it to handle the twisties instead. Should I use the .890, the .870 or the .810 torsion bars? Thanks a lot.

It is generally accepted that be larger the torsion bar the stronger the spring rate will be better handling on road courses will be