For a beast I would choose a monster truck (upgraded savage flux) or a truggy.
It must have plenty of ride height & suspension travel and a very strong transmission, to sum it up.
I wouldn't go with an e-revo. I had the brushless version, it was good but you don't mix power and plastic driveshafts.. You would have to upgrade it massively to make it handle rough terrain. An other good option would be a e-converted SAVAGE
Concerning the electronics you can't go wrong with a RX8 speedo and tekin or NEU motor