Has anybody ever built one of these model aeroplane's ? These seem to be old kits and finding the motor/gearbox for it took a lot of investigation. But the 7-8 NiMH min.720 mAh cell battery pack for it is proving impossibe to find. Can any other battery pack be used instead for this Spitfire model? This uses a 300/6V motor (Griebel) and a Griebel 1:7.7 gearbox.