sound like the reason you are having problems is because your car has drums at the rear and the mk4 probably has discs. if so i think you might have problems with spacers too because of the offset.
i have 16" montreal 2's on my mk2 and had to drill the hubs for the 5 stud pattern cuz spacers would of made the wheel interfere with the arch.
if i get chance i will pop one from my mk2 onto my mk3 rear and let you know later.