I am building my first smoker and cannot get the template to work on my computer. (maybe it is operator error) I have a cooking chamber that is 57 inches in lenght and 28 inches wide at the center. I need help computing the firebox size, number and size of openings in firebox, opening to the chamber from firebox, and stack height and diameter. The chamber is an old LP gas tank we have cut one end cap off of. Help please! Also, what is the reccommended height from the bottom of the chamber to the flow plate?