I have used both the 40mm and the 44mm Screamin' Eagle carbs in the two installations I did. I preferred the 44mm.
The original setup that hit the market from ZOR was basically an adapter, and it worked. But both ZOR and Petroworks now have versions that involve remachining the original intake to allow a true side draft approach to air flow. The adapter version added too much of a bend which restricted airflow. You will want to get the whole kit that includes that intake. I think both companies will ship overseas.
Here is a shot of the Petroworks version. I had it installed and burning rubber in one afternoon.
