nice project!
why You using type9 gearbox? do You think it will hold almost 300Nm torque?
pro's do not prefer, they say t9 is weak.
MT75 works perfectly and have VSS for ECU.
Or use old essex Type5 unless it has only 4 gears, but heavy duty as well as its needed.

we are using both of them, in drift sierras.
didn't try the t9 yet, we still have fear about the weakness.