Help with wiper upgrade, PLEASE!

I am restoring a 74 Duster and am having some issues with the wiper system. The current wiper motor works fine but I wish to add an electric washer system to the car as this car had the old foot pump that has long since failed. I need to find the wiper switch that supports the 2 speed motor but has the electric washer funnction. Can anyone provide a part number or part??