If you got the time, money and want to, I'd build the box around 4.25 cubes. Try it out, play with some different ports, decrease the size, play with port orientation, etc and see what you like the best. That's what I did with my n2 while I waited on the others to come in.
But if your like others and want to build the box and not touch it again try 3.5 cubes, 55-60 sq in of port and a tuning of 32 hz.