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Yes, I ordered it from an Omega boutique and I might PM you the cost because it's somewhat eye-watering (though still £140 less than the bracelet from the new '57 Speedmaster, which looks basically the same to me except that it has a push button micro-adjust in the clasp). The part number is 020STZ012773.
Here's a pic of someone else's FOIS with the 321 bracelet and Forstner end links.
Yes, it is. It will fit the FOIS using the Forstner end links.