Well, I run a Mamba Max and a Wanderer motor in my Revo. That could work, but if you run anything over 12 cells or 3s lipo, you have to run a BEC or an RX pack. Novak HV systems arepopular and I think they're finally making some progress on the Mamba Monster Max. All of these would be about $200 to $300 new, but I bet you can pick up a used system fairly cheap. I think you're going ot need an XL size can and something to spin it without overheating, which is a combo of your set up and gearing.
I think the cheapest route would be the MM, XL can and a RX batt, running 12 cells or a 4s lipo.
Bullet proof system without thinking, this is your best bet:
http://cgi.ebay.com/Novak-HV-Pro-High-Voltage-Brushless-4-5-Motor-System_W0QQitemZ170280952339QQcmdZViewItemQQptZRadio_Control_Parts_Accessories?hash=item170280952339&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318Also, don't forget you're going to need a couple of 5mm pinions in the correct pitch.