Have VW ever built a 300bhp car on this chassis??? Nope - and they aint about to start!!!!
What makes you think it isnt suitable for 4wd?? The rear subframe mounting points are exactly the same, you can bolt it up, you'd just need to raise the boot floor for the fuel tank and fit the prop shaft, most of the rear suspension componenets are common to 4wd now that they are using independant rear suspension throughout - it wouldnt be thats hard to do in a workshop or at home, let alone in the actual factory with a bare shell.