I have looked at that page before. No experience with it, but a lot with the F200A. Should you get around constructing it, I doubt you would feel the need of a supertweeter or tweeter in general. They go up very high, without help.
The other doable or done for you cabinets that do justice to these drivers are the Bob Brines FTA-2000s. Very heavily built, imposing, with a sound that would make your jaws drop at the weight, speed and intensity of presentation. I have them, so do at least 3 other people across the country. Worth every single penny...something that I can not say about the majority of speakers out there. It beat almost every single commercial speaker I have heard in my life (Gershman, Infinity Kappa 9, Omegas, SAP, Aerial...)