I got the 1.6 mm Brass collars and the 5mm OD/2mm ID SS washers in.
The brass collars needed to be drilled out to 1.8mm to fit the SS tube and while the washer held the stock silicone oring in place nicely, it sits slightly askew because while the spec says 2mm ID, in measurements its 2.2 mm. So there is about a .4mm play between the washer and ss tube.
This setup retains the auto adjusting feature and looks like it seals the pin in the 510, but it doesnt have a way to secure the
juice bottle tube onto the ss tube. The length is about the same, maybe a 1mm longer than a classic FD510 set up for bottom feeding. I could mod the end of the hollow brass pin to be shorter which may actually make the set up to be 1 mm or two shorter than the FD Classic.