Don't recall anything for the CS engines, or the 8/1 upwards.
The basic CS speed adjuster works fine, you can adjust the governed speed at will by moving the knurled nut along the adjuster thread.
If you needed to switch quickly, set up a couple of spacers so you can pack the adjuster nut out by a known amount to give the higher speed, or make up a small lever to pull the adjuster nut back to a stop.
Peter