My ears were burning lol...
Gearbox wise you will need to go MTX to handle that power. You have stated what box your intending to go for and its what I have gone for.
Before you chose anything though you need to decide what the car is used for.
If its a track/racer a road/track car or just a road car.
Bearing in mind to handle the power well you will need to sacrifice some of the refinements you currently may have.