I also have this as reference.
It is an Esprit 13' 6" with a buffalo main and unidentified jib. The Buffalo has a bigger rig than the Esprit and the jib is coming right back poast the mast. I think this cheap power upgrade might be more successful with a Nacra style bridle foil which would bring the jib forward and lower and create a better slot.
As it sits I am sure it would backwind the main.