Think 6S is the way to go with this kind of cars!
I'm running the Motnoica P81 Electron with some minor options like adjustable rear swingbar.
I like this car, good quality and durability only "problem" is to get spare parts quickly.
No heat issue on either ESC or motor, top speed should be around 100-110 km/h.
For next season I have added 2x 30mm fan to keep the motor even cooler but this is really not needed.
ESC: Tekin RX8
Motor: Tekin T8 2050kv
Battery: (6S) 2x Orion 3S 45C 3800mah
Gearing: 18T/45T 5.80 FDR