Well any motor big enuff, your gonna need very high voltage to spin it fast enuff...
Here are a few choices
http://www.hobbycity.com/hobbycity/s...idProduct=2114
http://www.hobbycity.com/hobbycity/s...idProduct=2113
http://www.hobbycity.com/hobbycity/s...idProduct=2101
PS-i am doing a DD conversion at the moment also
Benjamin White
R/c Monster Team Driver
Jq the car, LST, Sportweks turmoil pro
Unconventional Techniques, Superior Results