I'm with Jajceko on this, unless the gearbox is completely different in the 1.4 to all other models (unlikely) it should handle the extra grunt without failure, same for the clutch. Even if both fail he has backup units ready to install.
Suspension, brakes, chassis, etc are the same on 2.0Ltr diesel and 1.4 petrol, so handling shouldn't suffer too much with extra power, and I'm sure the torques won't be much higher than the 2L diesel put out.
As I said earlier, everything could go wrong, but that's life.
Jaj' knows the risks and the positives and is willing to give it a go.
If it fails, swap out & try again, and if it works HAPPY HAPPY FUN FUN JOY JOY !!!
Good luck mate, and keep us informed, some of us are interested in your project and really hoping it works for you
=== edit ===
That vid shows 0-100kmph (60mph) in about 10 seconds