please expect to modify the design slightly
if I remember correctly it is designed to use the YM2718
there are two sections you can attach things to, the small one allows you to use the low toque high speed motor directly while the large hub lets you use the high torque output of the gearbox
use the stil file named "assembly.stl" to see how the thing goes together
it has good torque while maintaining a decent amount of speed
I recommend you print this from PLA