Mike 1 and 2 should be identical meshes. Set the sharp teeth morph on Mike 2 only, no other morphs, then export the head only as an OBJ. Deselect all tickboxes except "save as morph target" then save it and load it onto Orc Mike then it should work fine. This assumes the Orc Mike you have is vanilla, ie you haven`t edited it and re-stitched the head onto the origianl model.