On that note, wasn't it determined in another thread (I'm hoping
CV-6 remembers it; IIRC, he was part of the discussion) that Stronglight's taper is also
deeper on the drive side? If I recall, it was
not ascertained whether this was just a deeper cut of the same LH taper, or whether the actual start width is narrower or not.
While I share
verktyg 's opinion that a fairly used Stronglight crank can be installed on a JIS spindle if the taper matches up from previous installations, I really wouldn't try to put anything but another Stronglight crank on a Stronglight spindle. The spindle is just too different from the rest - even TA - and I usually find it better to pass them on (or hoard them) for when they're absolutely needed.
Since
Germany_chris says Italian equipment can be found easily and cheaply where he is, why not go with a Campagnolo Nuovo Gran Sport or Triomphe crankset with matching French BB? Methinks these bits will be much easier to find in his location, suit the period look (if that's a consideration), and open up the opportunity to use compact gearing:
-Kurt