VERY cool!!
Just guessing, I'd say about 3 1/2 cuft should just about do it. I'll have to look at the books to figure out what the port size needs to be.
Tell you what though, if you want to bring them by, we can measure them I can tell you exactly what the Theil-Small parameters are on the drivers and then we can do some quick modeling and confirm the proper box size and port dimentions.