I don't know if a 60t spur is going to work with a 20t pinion. I tried running a 62t spur with my 20t pinion and I couldn't adjust the motor down far enough to get the gears to mesh properly. I stripped the spur in about 60 seconds. I had a zip tie around the motor for my temp sensor though so that probably took up about .03-.06" of adjustment... so maybe you will be ok, just a heads up to watch for that. I have 1/8 diffs too and right now I am running 65/20. But I haven't been able to really drive it hard and test the speed since I have built it because of the weather here. Good luck.