Converting my CRT .5

First off, hi. I am Eric. This place seems to be full of knowledgeable people and I hope to learn a lot here.

With that out of the way let's move on to what I came here for. I'm going to convert my CRT .5 since I'm tired of nitro. I'm going to be using the RCBros conversion kit, a Mamba Max, and a Medusa MR-036-050-3300V2-5. I got most of it sorted out. Except for one thing, gearing. I know I'll be using the stock spur so I'm going to need to know what pinion I should use. The truck will be run on 3S LiPos and use the stock 2.2 wheels.