The gear box was to turn bigger props with less amps. In the stock form, I flew mine that way, I would get 5 minutes of powered flight MAX It was under powered and flew on the wing only. Not worth your time to try and fly it that way.
The motor I linked to will run direct drive, ( no gear box) with a 12X6 APC "E" prop. With the battery, motor, prop combo you will have 3 times the power and 3 times the flight time. You will have to make a mount for the brushless motor. It could be a simple wood box bolted to the firewall or stand offs.
When I order from Hobbypartz, I get it in 2 days. I am close to them though.
Another place to get about the same setup
Motor
http://www.valuehobby.com/power-syst...outrunner.html
ESC
http://www.valuehobby.com/power-syst...-40a-ubec.html
Battery
http://www.valuehobby.com/power-syst...200mah-3s.html
Buzz.