There is few options on 380 motors.
380 Sensored: Novak THREE-80 MICRO 18.5T - 4,400Kv - 82Watt
There is a few options on the 540 sizes.
540:
Novak Ballistic spec 25.5T - 1,550Kv - 82Watt
LRP stock spec 21.5T - 1700Kv - 148Watt
http://www.lrp.cc/en/products/electr...-215t/details/
GM PRO 21,5T metal - 21.5T - 1650Kv - 140Watt
http://www.graupner.de/en/products/9...1/product.aspx
I don`t know about a lower turn 540 motor who is not a crawler motor.
I have some doubts about using a crawler motor.