Looks very nice snakes. You are going to want a big, adjustable draft door under the wood door. This thing will want lots of air to keep that fire hot.
I double insulated my fire box with rock wool and then fire brick. I welded 16 penny nails so the tank so the rock wool wouldn't get squished. I placed a cut up 55 gallon drum to set on the nails and laid firebrick on top of that.