Ok, used Brian's calc again (thanks for the updates BG) and a 950-1000kv motor with a 12t pinion would be my best suggestion. Also, if you do not have batteries may I suggest going with a selection of lipos that will allow for 10s and 12s. Maybe 2 5s packs and a 2s you can remove to get 10s... Or a 6s, 4s, and a 2s. I think 10s lipo would be better, and allow for a larger pinion, as the small pinions on a large spur wear much faster as they have to make so many more revolutions than the spur.
It's a temporary update. There is no top speed cap right now, but I think there should be some kind of limit, just not sure what. Voltage is now capped at 15s (55.5v). And, be aware that the suggested motor list is being generated only from the motors I have in my "database", but there may be other motors out there that could be suitable.