Options for outer shell: mixing own mortar

I have an over supply of the four ingredients for the oven mortar, and wonder if one can use Portland cement, fire clay or lime and sand to cover the chicken wire and insulation? I am going to have a wait time longer than reasonable to obtain stucco, and from reviews on most of the mortar mixes from Lowes, there is a lot to be desired of Quikrete or Sakrete.