Jomz Shakes,
Sorry you are having so much trouble. I to have been thru this, with 2 differant Z's none the less. I came to the realization that pulling the motor was the only way to go. You can then get at the bolts, clean up the threads and replace the manifold gaskets easily. I did not put the heat shield back on. I had both manifolds jet coated. I then put the manifolds back in place. This was easy to do. Put the engine back in the car and I was ready to go. I hope this helps out.