I found this info in the manual that is posted in the Adobe format. I found these specs but don't quite understand what they mean. Is the "camber unladen" specification here the arch listing that I'm looking for? I'll have to type it out, can't figure out how to cut and paste off an Adobe sheet.
Suspension System Asymmetrical semielliptical leaf springs
Leaf Springs 4
straight span mm (in) 1196.5-1,203.5 (47.106-47.382)
Camber (unladen) mm(in) 72.5-83.5 9(2.854-3.287)
Spring Constant N/mm (lbs/in)
-as installed
at load of 1,000-2,500N (220-551lbs) 24(134)
at load of 5,500-8,500N (1,213-1,874lbs) 56(314)

I'm going to ask the spring man what he thinks, and hopefully that will be what I need. I put the Summit Shackles on, and it basically levelled my Raider out.