I would strongly suggest going to at least 4S lipo for a truck the size of a Revo. For inexpensive motors, you could go with either the Feigao 8XL or 9XL. For a better motor, you could go with either the Lehner 1940/8 or 1940/9.

I would advise against running the 3S packs. Any motor that will deliver any sort of acceptable performance on 3S is going to draw way too much current and things will get hot.