The "speedo ratio" value in the right column of Barry's chart will often have a "W" in front of it, and will be in small font at the bottom of the speedometer dial/face.
Look for the final drive ratio stamped into the grey metal top surface of your final drive, near where it bolts onto the swingarm housing in which the driveshaft passes. e.g. "32 / 9" .... this would be used with a "W1318" speedometer.
Some R65s came with 31/9 final drives and some came with 32/9 final drives, and some had their final drives swapped out by previous owners over the years. And, sometimes speedometers were swapped out rather than being repaired, as the odometer function does have a tendency to fail on these, and not everyone payed close enough attention to the various ratios.