Are all Klipschhorns, save those with custom upgrades, created equal? Any variations in particular to levitate towards or steer away from?
There's plenty to read on the Klipsch forums as far as opinions on this go. The drivers and the crossover have changed over time. I would look for the K55M mid drivers with metal horn bodies (as opposed to later models using plastic for the body - I would also damp the metal horns with damping material such as Dynamat or the equivalent sold cheaper at Parts Express, or with plumbers caulk), and the K77 round-magnet tweeters (as opposed to square magnet). I would actually recommend replacing the tweeters as a high priority (unfortunately this requires some effort as the better drop-in replacements, like the Beyma, are a bigger form-factor. I have heard the Crites drop-in replacement and was not at all impressed - go for the Beyma or Fane). Big, immediate gains can be had there. The crossover would my next target, especially if an older speaker. With the LaScalas the desired stock Xover is the AA model. I'm not sure what the Khorn's might be. I believe the speakers that conform to those components I've mentioned were late 60's to early 80's. Obviously if you can find a pair locally you will save some large coin and headache on the shipping.
Marco