G'Day Gav.
I also designed up a progressive adjustable cable cam, with a cable from the pedal to a 1:1 ratio pulley that is locked to another eccentric lobe that pulls another cable to the throttle bodies.
At the moment its maximum reduction is 30% at zero pull to 100% at 60deg, and full open at full pedal.
Its adjustable almost back to 1:1 by rotating the Cam and lobe.
I couldn't find anything on the market like this, I will probable have a go at making it.
Dave
Its designed to suit a Lokar throttle cable end.