If I would have known how bad the skin really was I would have also repaired the original quarter. The problem was that this was my first car project ever and changing the quarter panel was one of the first sheet metal works I did, so I really didn't have any "eye" for the possible issues back then. After many many hours of banging, cutting and welding I ended up with something decent. It still has pretty much bondo on couple of places and the shape isn't quite right if compared to the original, but it is very hard to see without knowing it.
The skin is mainly good for cutting out patch panels. The wheel well is fairly close to what it should be and mayby the lower rear part of the skin is also usable. The door opening edge is horrible as is the filler panel opening and side marker recession. Also the curvature of the bodyline where it bends into the tailight panel is just amazingly bad.
Well, hopefully my next project goes better in the terms of using repro panels.