I just don't think those drivers are particularly good value, especially if you don't have a crossover designed specifically for your cabinet.
Since you're in Japan, why not try a Fostex driver? Should be easy to get hold of. The FX200 is highly spoke of on the fullrange forum. You can do the modeling for yourself using Unibox.
For a more conventional design, it would be interesting to try making a version of the Ellis 1801 maybe. Dave Ellis has a forum here, you could ask him about whether it would be feasible.