torsion bars

The performance handling book says the following for A-Body:

Slant 6 Diam. .83" Rate: 92#
2-bbl V8 Diam. .85" Rate: 101#
4bbl V8 Diam. .87" Rate 110#
383 V8 Diam. .89" Rate: 120#

I can post the part numbers for the factory bars I have in this book if anyone needs it. They are stamped on the front or rear, or sometimes both.
My Duster was a 318 car with .85" Bars on it. I added the 360 and 727 and the handling went WAY down (car was lower also, had to crank those adjusters). I recently rebuilt the suspension and added .87" bars. WOW, the handling was night and day different. Even without the the sway bar on it handles pretty good. But, I dont race the car (yet), so I'm not sure what bars are right for that. Hope this helps!