Recently I've been looking into the need to redo the head on my 83zx/non. I've been told by some of the head rebuild shops not to rebuild unless I'm willing to rebuild the whole engin. They've said a rebuilt head will "blow out the bottom end". Could somone explain to me what they mean by this ? Rings ? Pan gasket ? Front and rear mains ? Main bearings ? or all of the above. I could deal with gaskets and seals but not sure I want to deal with rings and mains at this time.