50mm MedUsa gearing for Rustler?

[Unsullied_Spy]

I want to put a 50mm MedUsa motor (4800 KV, 5mm shaft) in my Traxxas Rustler with 32p gearing, but I have no idea how to gear that motor. I want to use a 58T or smaller spur gear but no idea which pinion to use and with the cost of 5mm bore pinions I'd like to get it right or close to right the first time.