Porsche 915 or 930 gearbox in my 1302s

[cobra]

Hello

I am bilding a vw 1302s road racer. And I nead a new gearbox. And I nead to get the engin asfar as posibel in to the car. I do not whant to cut the irs tube. Mye engine is a mitsubishi 3000gt vr4 twin turbo. What is the best gearbox for my setup. 915 from 911 3,2(oil cooler) or the 930 4 speed turbo box. The engine has 320 hp and 475nm. Do some of you have god foto`s of 930 4 speed gearbox in vw. Help me decide.