We route ours under the intake with the same tb. You can mount a cable bracket to that heater hose bolt and pull the throttle lever downward from there. There's enough pull to get wot.
Am I reading right that you fix the intake-end of the throttle cable at the back of the engine and route the cable itself under, to the TB? I haven't considered placing the bracket that far back, i'll have to see how it would work out.