I would personally recommend you keep the kick down function available, and perhaps either move the function to a later model pedal mounted style or, as I mentioned in my previous response, place a press button on the gear stick to enable the passing gear solenoid...(aka Kick down solenoid).
It is not that hard to do, especially if you are doing re-wiring etc...
To wire a manual kick down button, you will need an ignition hot power source, fused of course, to the press button, out from the press button to the kick down solenoid fitting on the side of the transmission. When the truck is driving, pressing the button down will engage the solenoid, dropping the trans into 2nd or 1st, depending on the road speed at the time.
