I plan to use Wrangler Springs, very soon.
You should check what Chris has done with them http://hsp.rockcrawler.com
He did use a different drive shaft, but that wasn't because of the YJ Springs, he has had that drive shaft for a while.
CSC has a complete bolt on for the YJ's, and so far it is a shackle reverse, but they are working on a non-shackle reverse kit too.
Chris and Ron are working on doing it thierself (non-S/R) and to keep a better approach angle they are having the front YJ spring shortend to match the length of the rear Samurai spring (only on the front 1/2 of the spring), this will give them the benifit of the YJ ride and longevity over any other spring setup.
They use the front YJ's in the Sami rear and the rear YJ's on the sami front. (I think)
Fred from Canyon State has a great kit, with all the hardware, that will keep everything safely inline. Check out thier Website. I followed Fred through one of our toughest trails here in Arizona, and he "never" pulled a wheel off the ground, due to a lack of flex/articulation, and the ride his set-up give is smoother than anything I have seen.
From what I have seen so far, you will only need a 2 inch spacer or slip yoke for the front, and a 1 incher for the rear, no "super expensive" drive shaft needed, unless you drive like a nut.
Read Chris's write-up and check out the Flex!
Once you see one of these YJ setups on a Zook and at the lower cost than most out there, I am sure you'll go for it too. IMO
Asian Auto Parts
"We make your Suzuki ZIP for less"
There is a very fine line between "hobby" and "mental illness."