Hyper 8 Conversion: Need Some input

[Thunderbruiser]

hey fellas i am planning to turn a hyper 8 into a bl since i'll be getting a losi 8ight for nitro racing to match my losi truggy...anywho i will most likely be running a 4s setup eventhough if i bought another esc I could run a 6s 8000mah setup

items i have right now:
mm controller
feigao 10xl
18 tooth pinion
stock center gear
could run 4s 8000mah setup
i think with the speed chart and geared 18/46 it should go like 40mph or something lol

i want around 35mph-40mph but i want runtime more than anything...and i am afraid the 4s/10xl won't hack it what would be a good direction to go with this?

I am also working on a mantis truggy but that's later

please lead me in the right direction...i have batts just need a better esc/motor combo i think

thanks in advance fellas