Except in the case of Klipschorns, you already have in its junior form, the La Scala, an "A" rated speaker setup by Stereophile.
Just like the Citation Deuce, however, there are well known deficiencies than can be easily rectified. Drop in a tractix midhorn, and either keep the original Atlas mid driver, or get a JBL or other higher end, better performing driver. Drop in an APT, Beyma, or JBL tweeter with a tractix or 100x100 horn, and you are good. Drop in an active xover and time correction, or an ALK based xover, and you are even deeper in Heaven. PWK was a very active supporter of testing and modding his Heritage speakers, and I know that from personal experience.
The Klipschorn is a Klipschorn due to its bass chamber, not the tophat. PWK wasn't too concerned with the top, other than it was capable of doing what he needed. That arose out of his decades long struggle to source mids and tweets that were serviceable.
The ST70 is characterized by its good transformers, and by the very weak front end board and compromised power supply. The majority of the top end tube amps are often first characterized by their superb transformers, and then by not allowing anything else to compromise or limit the delivery of that superb power and bandwidth.
All those upgrades, with the new TE chassis for the ST70, is $1336. I would get a knackered 8B, some spraypaint, replace the three power filter caps under the chassis, and $600 of excellent tubes, and be ahead.
