124mm is pretty long- even the later post CPSC two ring of 115 add in an additional cog and 121-122.

I think to get that wide one would need a mtb spindle- which complicates things as many Mtb bottom bracket shells were73 mm wide

french threaded and 70? Are you positively sure your bottom bracket is 70mm wide?
french is typically 68

last note- Campag triple spindles were designed for the earlier design Record cups ( the thin cups) without the reverse spindle bore threading.

Campagnolo can be a hot mess sometimes