Consider having the draw off boxes sitting lower than the pans and having the valve on the side. This will allow all the syrup to drain out of the pan and you dont have to do the maple pan shuffle to get it all out. It is also a great spot to add a fitting anlged down into the pan for a thermometer port. The boxes on both my flue pan and syrup pan are built this way and I like it alot. It gives a few advantages such as setting the pan down on a flat surface to clean or whatever, The drawoff valves are not on the bottom so it allow the pan to sit easy. Also it is easier to clean as there are no elbows to reach into and scrub. The only other thing I would be thinking about is making sure you get some nice high sides on that with a nice bent lip on the tops for strength. Doesnt take long for pan to boil over if your not on your toes. My finshing pan is a 2x2 and 3 dividers is perfect so with a longer pan I would have four sections also.