You could just get the 600j, one step up if you are really itching to get something. Going overboard on the ESC does not hurt anything -
http://www2.towerhobbies.com/cgi-bin...?&I=LXHVA5&P=0
This would be another option depending on exactly how high your amp draw is -
http://www2.towerhobbies.com/cgi-bin...?&I=LXMRK2&P=0