Which Torsion Bar?

QA1 or Competition Engineering shocks are good

I run the Comp Engineering shocks and stock slant 6 bars (.810" diameter) in my aluminum head BB Demon - but mine is setup for drag racing -

I would go with these or larger like others have said and maybe look into front and rear sway bars as well if the lower control arms have the tab for it..

what is the wheel combo on the car? still 5x4" bolt pattern or has it been converted to the larger 5x4.5" (5x114.3)

being it has a 185 series tire on front leads me to believe it has a 4-5" wide wheel in front meaning a 225/60 will not fit with out going to a wider wheel.. get a measurement of the front wheel - if it's 5" wide you can run up to a 205/65-70 which will handle much better than the 185/55 currently on it.. I would also change the rear to a 275/60


Torsion bars - (.920" diameter)
http://www.summitracing.com/parts/dcc-5249151/overview/year/1968/make/dodge/model/dart