This is my first time building a Smoker. I have average welding and cutting skills but lots of time to do it. I have a huge pipe with ends on it and legs that was given to me. It is 5/8" thick, 24" outer diameter, and 63" tall. It is old and rusty. How clean does the inside really need to be before using? I don't want to take up too much room in my backyard and I do have a crane and forklift so I'm going to try a vertical single pipe design to minimize the space that will be taken up. I have tried using differnt "Smoker Calculators" but none of them are for this design and I really don't want an offset box taking up more room. Let me know of any hints, tips, ideas, or warnings you might have! I want to do it right the 1st time!