advise on vertical reverse flow insulated with kitty litter and with temp control

[SaguaroSmokinAZ]

I am wanting to build my own smoker and have chosen to build a vertical smoker which is insulated and with a temperature control system. The smokers I have bought thus far leave a lot of room for improvement, and I just can't afford to purchase s custom made competition smoker that costs more than my house. The cooking chamber outside dimensions will be 52" X 40" X 40" using 12 and 14 gauge steel. The firebox will be 22" X 40" X 40" Between the fire box and cooking chamber is a 4" X 40" X 40" water tray and grease shelf. I am having brain freeze when I ponder the most important aspect of the smoker--the air flow ventilation system. At the top of the food chamber is a 9" diameter smoke stack. I am going to utilize the 2" ball valve with the BBQ Guru fan attached at the fire box. To be honest, am just not positive the size and position of the crucial and critical smoke/heat from the firebox to the smoke-box. Any advise will help melt the brain freeze and add to the aroma of Good smoke.