You can change the carb & ignition system, but don't forget the main reason these governed systems were installed on big trucks in the first place. Their purpose is to limit sudden rpm changes in the motor. Big trucks carrying heavy weight don't tend to like sudden rises in rpm because sudden rpm changes tends to break stuff like rear ends and ujoints. It is especially a problem if the truck has a big block.

With the governed carb, if you stomp on the gas, the carb slowly adds rpm to eliminate a sudden jolt to the drive train and save parts. When you remove the governed stuff and stomp on the gas, the motor will respond and take out the weakest link, probably nearly instantly, depending on how much weight is on the truck.

Drive accordingly. Gene