As was asked, I went ahead and added the changes to the model. I went into maya and changed up the the lowest division of the model, merging the sails on the back and adding some geometry for the throat. I then refined the UV map due to the changes in the mesh. I had some initial concerns about adding this geometry as sometimes it can be too extreme and Zbrush is unable to cope with the projection.
My worst fears were confirmed. Zbrush went crazy when I projected the high res details from the original mesh onto the new base. Smoothing and moving the mesh was not enough and I could not control the madness. I realised if I wanted to add the throat geometry a new model would need to be created, so I decided to get rid of the geometry and just fake the detail when I create the texture map. I will explain this to Andy and hopefully he will understand.