Hi. In response to your torsion bar question. I've got an E-body that originally had a 340 in it and was converted to a 440 clone. The torsion bars were .870", but I wanted the car to handle well. I installed a pair of .960" improved "B/RB" and Hemi handling bars. Allthough the 440 weighs more than your 340, I found my car handles quite well without riding too stiff. If you want your car to handle corners without feeling like you're "floating", I'd install the .890" bars. The .920" bars may be a bit too stiff. Also, a sway bar would greatly improve cornering stability. I hope this helps.