I just scanned the pictures I took back in '95, when I built a single Klipsch bass horn to be used as a sub. This horn is based on an AutoCAD 3D model. The plans you'll find in the download section. Maybe these pics help to answer question on where some of the small parts in the plans belong to. I also want to thank my friend Robert who helped me a lot building these horns.
And this is the driver I currently use (obsolete Eminence type):
If I would build an other one of these, I'd use thicker wood for the
internal parts (like 22mm). If you touch the inner parts when it
plays loud, you can feel (very small) vibrations. I would not say
that this is a problem, but an absolutely dead backchamber would put
my mind at rest.
A more important thing is the choice of the bass driver: Although I
did not try, I would start with the original Klipsch K33E bass
driver. The reason is, that the Klipsch basshorn is a compromise
speaker system: The horn is foreshortened i.e. it's too short for the
flare frequency and it's mouth is too small as well. Down at it's cut
off frequency it more acts like a closed enclosure than a horn. PWK
has most likely tested a large number of different drivers in this
corner horn. I think that he specified a driver at the end, which
conceals the weaknesses of the horn as good as possible. With most
drivers suitable for horn loading, the Klipschorn lacks deep bass.
Thus you'll probably obtain best results with the K33E. And it's not
even that expensive as you might think. It's like 120 Euro (approx.
US$ 135).