I have an 8L in my E-Zilla, with stock gearing and E-Maxx size tires. As for ESC, I have tried MGM 12012 and Mtroniks Truck. Yes, heat sink and fan for the motor are recommend, but nothing go up in smoke yet. My E-Zilla is ~ 9.5 lbs with 12 NiMH cells. With the stock tires, it should be ~ 9 lbs.
I think with 9L/12 cells/stock tires, the top speed should be ~ 50 km/hr.