Install a gas pedal long enough to pivot it a little below center with a strap hinge, and attach the cable to the bottom of the pedal. By tinkering with the pivot point and the attachment to the carb bellcrank you can alter the speed and distance of the cable movement. We made race car throttle pedals this way. An added benefit is that it's possible to close the throttle by pushing the bottom of the pedal with your heel if you use a push-pull cable like the type used for a PTO.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!