Something like this motor would be good for a maxx with stock diffs.
http://www3.towerhobbies.com/cgi-bin...?&I=LXPPY0&P=7
Now, stock diffs will most likely not hold up to the power... But the 3905 will be the best bet. That chassis you list will have to be cut wider in the center to accomodate the width of the utrunner. Anything smaller in diameter will lack the torque to startup under the load.