Seems odd to just buy bits when they may make no difference. I would get a trusted suspension shop to take a look first, and replace any of the factory stuff that's worn out, eg. ball joints, tie rod ends and bushes. Got any decent shops in your area?
Also, if you intend to lower via the BC's, you may need a bunch more bits to be able to get the alignment right again after the drop. What you need will depend on how low you go, so decide that first. For skylines there were a bunch of SydneyKid group buys that had all that info. I dont know if he did any Stagea group buys.