Gearing SP 8.5 in KF

[Npdp72]

Is anyone running a Speed Passion V3 8.5T motor in their KF?
If so what spur / pinion combination are you using?

I normally run a 6.5T motor using 76T spur and either 23 or 24T pinion.
I'm wondering if I want to run the 8.5 motor for wet / low grip races, do I need to get an even smaller spur to achieve the right gearing, think there's a 71T spur available.