I would use the 2 cell pack with the GWS set-up. The 3 cell pack will fry the motor in just a few runs. 2 lipo cells will be plenty for the stock GWS (depending on the gearing) Might not hover at 1/2 throttle, but 3/4 throt. is realistic. You can also re-time the GWS motors to get some extra "kick"

Tim