Does your Wrangler chassis have 4 leaf spring mounts or the front coil / rear leaf type? Have you tried asking Armark Internatoinal for your suspension needs? RIDE Inc could also carry some parts; same as with Joey M's 4x4 Extreme Shop.

I could pressume that the 4.11 gear can keep those tires rolling, just don't expect to have a topspeed of 120km/h with those big tires.