? on Installing setback bracket

I have a 20 ft cabin cruiser that had an inboard in it I would like to convert it to an outboard using this custum made bracket http://www.shareaproject.com/imageUpload.php?i=3672 ? what do you guys think of this it is 33 inches long another ? is how high do I mount the anti-ventilation plate from the bottom of the boat

Thanks Eugene