I think the dimensions given are the string spacing from low B to high C. When ordering my JAN III 5 string, they referred to it as having "45mm spacing" and thats obviously not the spacing between each string. Scratch all that, I just measured my LX JAN III and its at 45mm total, not spacing. the spacing on it was 10mm shorter than the total width, I would guess the 6 string would be about the same, 10mm off the total width given.
Regarding height, its adjustable, but I am not sure of the exact height on each end of adjusting. Comparing it to a Fender P bass I have here, its pretty much twice as tall at the lowest height, so that may be a problem if your using something that requires a shorter nut. The other dimensions I cant help, maybe someone here can find the exact dimensions for you.