He is referring to the hole at the bottom of the vee where your drive cable is exiting the hull. He is recommending that you elongate the hole to allow for easier adjustment of the angle of the drive. I would not worry about modifying the hull until you have run the boat. You can make some adjustment to the drive angle / height without elongating the hole. Significantlchanges may require the hole to be elongated though.
I would not be too concerned about doing it yet. Run it and see how she goes first
