You will need to change everything for the VR6.
All of the running gear, sub frames, driveshafts, hubs, brakes, engine, fuel pump, you will have no abs
You would essentially need to buy a VR6, and de shell it onto your car.
Just buy a VR6.
Its only worth upgrading engines if you have a good gti/16v. As then you are only talking a few bolts and a days work. Not a years work.
Sorry...