I had shackles on my SJ, it drove like a bag of s**t on the road, and still grounded out on steep hills. The spring shackles dig in.
Personally, I would go for a spring over axle conversion, or lifted springs.
Both can be quite expensive, but far better than lift shackles.
You can get shackles on e-bay really cheap.
If you do the S.P.O.A., its a lot of work (and cash) but better, and you can fit 31" tyres.
You end up with about 5-6" of lift in total.