If your car needs constant steering correction to maintain a line and the front end parts are tight like new, increasing your caster settings should alleviate some or all of the twitchiness.
If your car feels like it has a bad case of the Clem Kadiddle hops, or at least uneven dipping and floating, it's probably because the shocks have gone away. Replace the shocks.
Because your Mopar has adjustable front torsion bar springing, you can level out your car from side to side and front to rear by adjusting the torsion bars, (for instance, lowering the right front will raise the left rear, etc.), but doing so will just mask the real problem. Your rear end is sagging because the rear springs are worn out with the driver's side having lost more of the factory arch than the other. The short time fix is to have them re-arched, but the best fix is to replace them with new, not used, ones. Raising the rear ride height up in relation to the front will lessen any existing caster requiring the static setting increased just to maintain what's there now.
Modern gas replacement shocks (good ones, not wally world specials) will also allow you to run higher all around spring and stabilizer bar rates than the factory did without ruining the ride, making the car handle far better than these cars could when factory new.
