So maybe this would help. Is there a reason you want the back of the car jacked way up? You seem really particular about the front end being set to factory settings, but you seem to want the back jacked up 4-5 inches. There's a reason ESPO doesn't do +4 or 5 springs because it really messes with the handling to the point that they don't want to be liable for the resulting wreck. The reason I'm trying to help figure out this is because I've been using ESPO springs for 20 years and have +2 6 leaf springs on all 3 of my 1970 Darts and they all look just like the photo you posted of your Dart, 2 inches over stock.
