the Faulhabers are great motors, especially where on need much power in a compact unit. The 3557 is a pretty pricey engine, and possible quite overkill when it comes to power on a 740) Can recommend to test the Servonaut TM120 motor, strong and a good price. (The one with a gearbox is called GM32U450) Use them with Tamiya trucks with semi tippers, twice the weigth of a 740 I would suppose, gets the job done. I'm not familiar with what motors are in the 740 originally, but have heard several complained about the power. Some even throw out the 3 speed, and put a 1 step planetary gearmotor.
https://servonaut.de/shop/de/product...595_tm120.html
http://rctruckandconstruction.com/showthread.php?t=7666
Here is a hobby dealer in Germany that have the Faulhabers, possible a bit better price than the industrial dealers, that likely also are in the US
https://lemo-solar.de/shop/glockenankermotoren.php
(the Faulhaber motors does not have the same 'engine brake' power as standard DC motors, more feels like turning a brushless motor, even they are not brushless)