Plymouth duster rear suspension questions

Hi everybody I am getting started on my rear suspension and was curious about some parts that I need to order. Purpose of a vehicle is mixed between daily driving and canyon driving. The front suspension is almost done and now moving on to the rear I have the following parts.
- Ford 8.8 with discs and limited slip
- rear bilstein's shocks
-US car tool spring relocation kit.

After browsing with some of the forum post here something that I think would match my front suspension PST 1.03 torsion bars and sway bar. Would be a set of Mopar performance leaf springs.

I'm trying to figure out which ones I should use
Between the following part numbers
P4529415 and P4529414.

I understand that the difference is 1-in arch but I don't understand what that means in the sense of suspension geometry and a effect.

Additionally I've read that these leaf springs take a 1-in bushing and so I'm trying to additionally find a set of rear shackles that will also work with the relocation kit and the new rear leaf spring setup. The ones that Mancini racing seem to be a fairly good price point and have polyurethane bushings but I don't understand if they'll fit my application as there's many aftermarket variables.

If part numbers could be included on the shackles/bushing kits that would be very helpful thank you