Jeeesh. Finally got it in. The motor seriously is huge. I choose to run a 25t pinion and man, that thing is huge also. Way bigger than the 18t I was mocking up with. Its a good thing I built in a lot of adjust-ability.
I had to cut the chassis out for the motor AND for the pinion. Since my motor is mounted up kind of high, the pinion mates up with a wider part of the spur which pushed it out more.
Turned out good though, I'm pleased. Truck's rear end it currently apart so no running just yet. I'm waiting on a new rear shock tower, mine was bent all to heck.