LOLOLOL, I find that a little funny.
There really is no bolt in option for the z's besides mckinneymotorsports.com, but still thats not a full bolt in conversion. You would still need to weld your spindles to the coilover they are selling i believe.
I'm actually in the process of install coilovers in my 240z, i am using cheap emusa coilovers "ebay special" because they are very cheap and im just trying to get the process and most of the work out of the way then oneday upgrade to better coilovers. I say better coilovers but i dont even know how these will handle yet so im specking alittle to soon,but i heard alot about them..
If you want a pretty simple coilover conversion you could do ground controls/section your struts, or you could just do like im doing.
buy some cheap megans or similer brand from ebay,buy zccjdm.com's kit and bring it all to a shop to be welded. Good luck