Ok, ok i'll spill the beans.
I have a set of the 38mm Amal carbs made by Norman Hyde, courtesy of my best buddy Brent at newspeedmaster.com. They are very well built and I can't wait to try these things out. They are the larger size concentric carbs (the throttle cables lift the sliders, no vacuum!), made exclusively for the 904 big bore Triumphs, by the company that knows more about carbs than I ever will.
I am going to fit them tonight onto Matt Lessard's 904cc 2004 Speedmaster.
I had to have a couple new braces made as they were damaged in shipping across the pond (no fault of Brent's). Now that I have them ready to mount, I will give them the official Dink test tonight if all goes well.
Stay
tuned 
They also sell a set of 34 or 36mm carbs for the stock 790s.
