Go through ESPO for the springs, and ask for them to be de-arched. You can use the springs that are on the car as a guide to figure out just how much. Mopar Action did something similar with their Dakota project recently, I'm sure you could get the back issue.

As far as shackles, Mopar shackles weren't the crappy auto zone pieces that you find today. I believe Just Suspension sells shackles that will fit your needs and won't skew. Their new website is crawling or I would give you the pn.

If you get everything and decide you need a bit more drop, you can flip the front spring hangers. JS also makes a 3 position adjustable shackle set, but it may not work with your rear valence, it's a tight fit.