70' Duster /6 torsion bar upgrade

I posted this question not long ago but it only went out to one member...I think. I don't do this very often so I'm still learning on the site.
Any way, I want to improve the drivability and driving stability on my /6 duster. The /6 bars are so damn slushy! I see used 340 a body car bars on ebay but don't know if they're worth buying ..about $100 or so. I really can't afford new ones at this time but should I wait anyway or would used ones be ok. I don't drive the car hard...just normal every day stuff.

Thanks all!