I think postage and other commitments got in the way.
Essentially, the TBs were bored out, sleeved with stainless tube, the resulting hole bored out to 40mm and filled with a new butterfly. They are beautiful, jewel like things.
But having said that, there's nothing there that a decent model engineer couldn't do (Jenvey and all seem happy to supply the butterflies, which are the really difficult bit).
The TB from a Punto 75 can be adapted for use in a Mk1 (or SPI Cinq) and gives you 38mm.