Probably not much help but I'm currently running a Hacker 21.5 in my M03 with a Tekin RS ESC just because I had them. It is motor timed and boosted and runs well. Just club racing with no Tamiya rules. Take the boost and motor timing out and a good Silver Can can keep up. Had a timed and boosted 17.5 Orion in it for a while and it screamed.

I run it on a large asphalt road course and the local guru says go for torque on motor choice.