The link did not work for me.
Here is what I did. I used the #2BA oiler points to mount the plate. Got some M5 fully threaded bolts, and ran a #2BA die down about 6mm. Threaded on the M5 nyloc nuts with the nyloc end against #2BA thread. Drilled through with 1.5mm drill. These become the studs to mount the plate and the scale body. Made some spacer washer to get the plate level, the back end needed 2.2mm thicker washer compared to the front one. The Ali plate to clamp the scale to the barrel is held by a 0.03mm fit. Made a top hat from a piece of capscrew shaft, has a 4mm through hole and a 5.03mm od. The 5.03 is a press fit to the Ali clamp plate that was reamed 5mm and drill tapped M4 . The Ø5.03 is a nice slid fit in the scale oval slot, and a M4 capscrew keeps it in place as well. As the barrel key is worn, this allows for the rotary movement and not effect the readout of the scale. I used the other end of the mount as a length stop. With the rack and pinion barrel assembly, the barrel protrudes 3/16 of an inch. I made the clamp with 4.5mm recess to the front and drilled a 21mm through hole. Used a screw driver to open and get it onto the barrel. If I need to change back to the hand wheel and barrel , I will be limited in total travel by the 4.5mm of the clamp. I thought that I had the plate at a 30 deg angle . Truns out it is actually 32 deg lol measured with the protractor ap on my phone.lol
Neil

Front mount point

rear mount adjuster spacer

Ali clamp block, 0.03mm interference fit to hold in place

The most forward position with limit stop

Using, new to me , phone app,Smart tools Protractor, to measure the actual angle it ended up being.

Neil