truggy conversions are pretty straight forward, especially those for which Mike makes a mount.

You could keep the mechanical brakes, but I've found them to be unnecessary. Motor braking has been more than adequate in all of the conversions that I've done. The only servo that I use is the steering servo. I use the JR Z9000T in my trucks and the S version is the smaller conversions.

A Neu 1515/1Y on 4S lipo with a Compro 16018 controller should be a nice setup for you. For something a bit milder, you could go with a 1515/2.5d on 4S for usual running with a backup 5S pack for nuttier speeds.