Looking for advise on Tandoor oven

[gbuy2001]

Want to make a Tandoor oven out of a steel drum (probably 55 gallon) and terra cotta flower pot. I plan to insulate the exterior of the clay pot with perlcrete and surround that with lose perlite (SIMILAR to what others have done on the internet). I plan to put a few inches of perlcrete on the bottom of the drum to thermally insulate it. What I am wondering is whether I need to use fire brick for the floor and to surround the fire or i can use iron. All the designs I have seen on internet use fire bricks, but I am trying to keep the weight down so that it is reasonably transportable (I will probably remove the "pot" when I transport it. Any inputs are welcomed. I was thinking if I use metal, it is also easier to use mix of fuel, inserting LP or placing coals above a grate.