No reason to not make a center feed. Some thoughts: first, you don't have to have just one passage from the firebox up to the smokebox. If you had two 6" pipes with baffles, it would help spread the heat out. Second, a lot depends on the design of the heat shield. I think I might make the whole heat shield out of 2 parts sloping down to a center "trench" made of angle iron which would lead the grease sideways to 2" pipe drains going straight down out the bottom where they would drain in use into buckets. I'd also add pipe drains at the lowest points on the ends to use as washout drains - you
DO pressure wash the inside of your smoker, right? Finally, I'd consider instead of adding 3/8" plate to the middle of your heat sink, to use a piece of flat ceramic kiln shelf which you can buy at any pottery supply.
Have fun, the devil's in the details. You can smoke meat with a clay flowerpot and a plate if you're creative enough.
seattlepitboss
