Torsion bar question...

Ive got a 1970 Dart Swinger im restoring and ive purchased a 1975 Dart custom parts car for the v8 K-member and disk brakes. Ive never done anything with torsion bars. Can i use the ones from the 4 door 1975 dart custom. Or do i need to find some from a 70s model 2 door dart. Or will the original /6 torsion bars work? Need some advice.