It still comes down to a new design if you want a truly massive advance in performance. Looking at that picture the twin props are positioned so as to direct the air blast over the top surface and into the deflected flaps and use the massive tip plates to confine the high pressure air as much as practical. So they have sort of a blown upper surface and ducted lower surface with the props feeding directly into the system.

On a modified conventional model we have a single prop spaced too far away from where the flaps are located so the blast isn't directed into the "sweet spot" . Your flaps will make some difference and teach you a lot but I doubt you'll get the full effect you think you will from an add on vs a full design.