Duuuuuuuuuuuude . . . .
Not only is the stock tank gonna be at a weird height if done as per directions, it's also too small. Try a six ounce Sullivan or similar. Shim it where you know it to be correct. Ignore the directions.
Also search the forums for more building advice. The control system, less the horns is garbage. The model's weight is also an issue. They build anywhere from 60 to close to 70 ounces. Assemble it with an incidence meter to be sure it's straight and square. Decent flyer, though. Have fun.
Rick