Gumper, that little bit of work is IMO a good thing to do. While I don't think it'll show any type of big number gain, it is what was said earlier above. It's the little things that make the engines tick best.
I would just simply have a smoothed out mating point where the intake and spacer meet. Nothing fancy, nothing trick, no extra grinding to be slick. Just have them meet to get ride of the edge. Let the air and fuel go past it nice and easy, no obstruction to crash into and tumble over.