Start with 75T spur and 17T pinion. If you can use a 45T 32 pitch spur and 11-12T 32 pitch pinion, that would be much more durable with the 3s lipos you're gonna use. If you find the motor getting hot at that ratio, use a larger pinion or smaller spur.
Good luck.
The name is Alawi. You can call me Al.
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