When I fitted the Walbro to my MA71 I retained the factory resistor to run the dual voltages as per the standard pump setup.
I had no problems with this.
However, a friend did exactly the same thing and you could tell when it was kicking from low to high voltage so he removed the resistor and it was fine.
If I was you.. I'd install it, see how it goes.. and if it becomes a problem then remove it!