RE: North Star Conversion
Here is a picture of both North Stars. The smaller electric one is about 60% and uses a Mega 16/15/3 motor spinning a Graupner 5.5x4.5 CAM Speed prop.
A possible choice for the full size Balsa USA version would be an AXI 4120 outrunner. You could reduce the size of the prop and increase the cell count to add RPMs and current until you reached 40amps.