I don't under stand why it's that low. I put S/S springs in the back of the Duster. It looked like a stink bug. I flipped the front mount to lower it.
Here's a pic. S/S springs 002& 003, 255/60-15's with the hangers flipped.
His car isn't low, I'd venture it's the same as your. Remember the Dart has the lower outer wheel lip, not arched up. Lower the edge of your lip 3" and it's about in the same spot as his.
Get the car together, then make a decision on where you want the rear to sit. Relocation and a mini tub makes it easy to stick tires under it. You really need to get the proper wheels so the tire fits the wells.