Hello Maui Man... Have you seen Currell's set of Concorde's?
BAC/Aérospatiale Concorde
You have the Pepsi there. Is much better and detailed than the Airigami model.
I used to build the Airigami models, many years ago. The web site, as you infer, is off. But you can still check on it by the magic of the Wayback Machine:
Airigami.net :: British Airways
Although I didn't find the Pepsi Concorde, the only Concorde there is not available to download (British Airways). I still have many Airigami models, but not the Concorde.
I recommend you to try on the Currell's Concorde. You can follow my step by step on one of those here:
New Concorde from Currell - Landor. 1/144
Best of luck, Maui Man!