CO pot is there to trim idle and partial throttle fuelling, so it doesn't have a 'default' setting like the ignition timing - even on a standard G40. Ideally it should be set with the car on a gas analyser once a car has been remapped.
The accepted wisdom is a resistance figure of 550ohms or thereabouts is a good starting point for the CO pot, which gives a bit of adjustment either way (rich or lean) if it's mapped like that - which is what we do.
All you've done is tweak the chip's idle/partial throttle fuelling to suit your engine/turbo combination by altering the CO pot.
CO pot does eventually stop turning, it's just a lot of turns between its min and max settings!