Another kit that has them is the Jo-Han Heavenly hearse kit. There is a lot of inaccuracies with them. The top part in the board is flat, where it should be rounded, and the bottom is rounded, where it should be flat.
I took one and corrected it by cutting through the hole in the top, and installing the skeg (fin) on the other side, and bent it at the nose to have the correct shape.
Now I have a corrected longboard. When I was 10, my first surfboard was a 13 footer. my sister had to help me carry it to the beach!
I took another Jo-Han surfboard and corrected it to make a modern surfboard. I re-shaped the longboard by sanding off and adding a pointed nose, cutting the hole through for the skeg, bended the nose up, and added wrapping wire for a leash.
Hope this helps.