oohms

For old dusty gear, a damp (not dripping wet) microfiber cloth works wonders. It takes off a lot more than you expect and is very gentle

Sorry, in the spirit of Klipsch DIY, i'm only giving people ideas. I get the feeling that distributing detailed plans (free or for profit) might go against that. That said, with a little work you can make your own plans

At higher frequencies yes.. but you can clearly see what is going on from photos on the net. (Which i have also more or less replicated in my design) Plus the compression driver forms part of the throat anyway, and people are doing silly things like using long throat adaptors

This might give you guys some ideas on approximating a K402.. coming up with the drawings was a fairly small part of the whole project https://www.stereo.net.au/forums/topic/232459-klipsch-k402-replica-build/

You can get it looking pretty close by using established measurements with some guesswork, tractrix spreadsheets and CAD