Hi
you don't need to buy a shock or a bush kit, you just need to buy the bushes that are worn. It sounds like you need a pair of shock bushes, and a pair of ARB bushes, and a pair of springs, If you are doing the overlanding thing then I'd recommend you buy the 110 HD Genuine LR springs for the back, and the 90/110 HD springs for the front. I would also get genuine rubber bushes rather than polys but thats a can of worms I'm not getting into now!
Mike