there is also the Hobbywing Max10 (non SCT version) supposed to handle up to 3s, though only 30-40$ more for 4s capability might be worth it for some.The brushless version of that truck comes with this:
3800KV RC540 Brushless Motor, Waterproof 45A brushless ESC
Appears they intend for it to run at max on 2S lipo. I'm not sure of the measurements of the motor... seems a bit generic.
This would likely work ok, you would need to increase the pinion size a bit to get the most out of it:
The castle sct sv3/3800kv combo would likely have been a good fit as well, but it's hard to come by. Can still find the combo on ebay:
However, the HW setup is likely better. Has a stronger BEC in it.
Guessing you could get away with something cheap like a goolrc setup:
Likely need a new pinion regardless what you buy, so you will have to figure out the pitch and shaft size, then go up a couple teeth over what you have now. Go too big and it will just overheat the motor/esc.