I doubt it would be worth it unless the shell is absolutely mint, and possibly not even then. You'd want to upgrade the brakes to cope with the extra power, as well as the Master Cylinder as I believe these are different to the 1.6 Driver upwards, as well as the wiring too.
If I were you I'd think about just buying a 1.6 driver, as these are very close to the GTI in terms of features and parts compatibility. Plus you would end up with similar power output and it would probably be alot cheaper!