I've been looking into this recently as well. 2000-2200Kv appears to be the ideal range for racing based on the info I've seen. Can size 36-40mm diameter (add a few mm to account for fins/heatsink), 50-70mm length. 4-pole motors preferred, especially if you want to run a small 36-50.

You would have to gear-up the 2000Kv motors for larger tracks.

I've seen folks mentioned they like the speed and torque they get out of the CC2650 on smaller pinions at large tracks but I've also seen some not quite as happy with the battery consumption.

I've yet to run any of this stuff so anything I've said is all just bench racing and the conclusions I've arrived at for myself. Sometimes it's fun to just put the biggest baddest motor in there and be done with it. I'm more of an optimize the system for the intended purpose kinda guy.