First, the Duster looks wicked...I hope you keep black wheels on that thing. :cool:
My buddy with a Hemicuda went through a very similar process. Ultimately, the re-arching solved his problems and I would have guessed that it would have solved yours too. Could it be that ESPO just provided springs that are too stiff? How does it sit with a full tank? Any thoughts on relocating the battery to the trunk?
I'm looking at Hotchkis springs which advertise a 1" drop but it seems like there are multiple variables that determine where the car actually ends up.
Can you say why you'd prefer to avoid the blocks? It may be the cheapest solution to your problems by a long shot.