the bass jubilee bin can be had as a separate item from a few dealers that would special order the bass bin from Klipsch
most all the Jubilee shown were put together that way , you can even order a choice of veneer as well with working with this established dealer .
there are very well established protocols on setting up the Jubilee bass bins from Ray Delgato ( the guy worked with PWK on design of the Jubs ) both passive & active .
All of this is well documented on the Klipsch forum .
You can get the Jubilee in industrial black or, as per the picture at the top of the page (which is current production style) with a Walnut, maybe Cherry front panel. You can put a passive on it or an active. Some prefer one, some prefer the other.
Big horn too big? You can get the smaller horn and make your own 'Khorn style' tophat to enclose it.
Regarding the massive size of the big horn... One thing is for sure... the larger size controls the sound better than a smaller horn. I had a chance to compare the large horn to the smaller horn (K510) while inside their anechoic chamber. The large horn was undeniably controlling the sound better. Meaning, you could stand behind the horns and hear less of the sound behind the large horn. The smaller horn let more sound wrap around it and go to the rear.
What does this mean? Ultimately, it means there is less sound 'splashing' around places where you probably don't want it (side walls & rear walls). It would give you a better starting point with regard to room treatments.
The 'Golden Jubilee' as pictured above was funded by PWK's wife. I understand she had two or three sets made. One went to the author of the autobiography (and he's since sold them), she might have kept a pair and the other pair is in the PWK museum at his old college. Come to think of it, I'm not sure she has a pair as the speaker I saw in her house was more like the one in the picture with PWK sitting next to it.