Spoke with a fellow named Chad at Sudco (the US distributors for Keihin FCR 39mm). I asked him about purchasing the FCR carbs for my application (904cc parallel-twin) and he said "nope, sorry." Apparently (according to Chad) Southbay Triumph is the only vendor that has brought together all the specific hardware to make the FCR's work on our Triumphs.
So, folks, - if you want this upgrade, as I do, start polishing your pennies.
-BT