Mine is direct drive, the motor is inside the saw's housing but open on the bottom. The blade however is housed within a metal enclosure of its own, not overly big, just big enough to allow an inch or or so on each side of the blade, and enough height to allow it to adjust all the way down when the blade/motor is lowered. The port for dust collection comes right off the back, down low near the bottom, of this box/housing the blade is in.
I think the dust collection works well because this box is as small as possible, which helps maintain a good vacuum. Maybe that will give you some ideas. Surround the blade area with something no bigger than it has to be and put a dust port out the back and down low..