Agreed - this is a superb write up on the ins&outs of XS trannies!
In many ways, it is similar to the process used by Rolls Royce on their car transmissions back before the firm was bought by the Germans.
Essentially, Rolls bought Turbohydramatic 350 transmissions from GM and then stripped them right down to the last nut, bolt and clutch plate. They then honed, shaved, lapped and polished each part until it was dead-nuts flat, straight, smooth and sized right in the middle of its tolerance band - and then the unit was reassembled using their Hylomar Blue aerospace gasket goo and a torque wrench. This process is known as blue-printing by hot-rodders.
The GM TH350 had a fine reputation for quality & durability in those days, but failures were not totally unheard of. Rolls, on the other hand, never, ever had any failures with their re-manufactured transmissions.
Of course, the cost would have been prohibitive to do that to every single Chev or Buick, but for Lady Penelope's Roller....what the heck!