Well...probably 6S. I know that for most basher trucks you'd only really want 5S as you suggested, and no more than 4S for racing with this motor...but I'm just gonna take Aqwut's approach on this thing; just cram in as much power as possible (though Aqwut would probably be fitting a Lehner 2230 lol). Hopefully the RWD will help keep temps down. The drivetrain can take it...
Rootar, don't worry...I'm going to change the stock tyres for something more meaty sometime, though I'll stick with having all four treaded. And the pic's much appreciated!
I think I'm gonna call this project, "RocketShip"...or does that sound stupid? Sorry, I kinda have a thing with naming my trucks lol.