The first thing is to be "conservative" -- Most stock RTR trucks (like the Rustler) have weakspots that can cause problems if you bolt on too much power (Some locals tried Novak 6.5's and shredded the transmission gears for example). Just look at all the things Traxxas "upgraded" on their brushless trucks for the Velineon power system...
Back to the key items -- a normal brushed ESC will not work with a brushless motor, so your best bet is to buy a "combo" of a brushless ESC and a "matching" brushless motor. The Traxxas Velineon combo is a real bargain, Novak sells XBR/10.5EX combo's that are reasonable. I would worry that the Mamba will be too much, but that's your call...
"If you cannot win, make the one ahead of you break the record."
Biff Racing Team #420 (Ah... The "good old days"...)
The local indoor Offroad Track: The RC Race Barn
TLR22-3.0, TLR22T-2.0, TLR22SCT-1.0