It is worth remembering the GTI has been out in europe for 1.25 years now and there has been a few things changed(fixed) on the early cars.
So basically most things are now sorted.
As for the 83 GTI if thats a mk2 alot of stuff was carried over from the Mk1 back then so most things were proven anyway.
I have an 83 Mk1 thats been totally reliable all its life.
I have had more squeeks and rattles and other bits and peaces problems (that i fixed myself) with the mk5 than i ever had with the mk1 lol.