In 1980, Liege most definitely included the Wanne/Stockeu/Haute-Levee trilogy, the Rosiers, the Mont Theux, the Redoute, most probably the Hornay and the Forges.
I'm not sure about the Vecquee but it was in there in 1979 (Thurau made his decisive move on it) just before the Theux. So I don't see any reason why they would have dropped it.
No Cote de St-Roch, it was added in
1990 as substitution for Stockeu which considered dangerous back then.
No Saint-Nicolas, added in 1998 and of course no Roche aux Faucons.
The finish was on the Boulevard de la Sauveni?re rather South of Liege. Flat finish. It had been become a classic between 1974 and 1989. The start back then was at the Palais des Princes Eveques. Classic too. Actually ASO changed everything when they started partnering the Pesant Club Li?geois (historical organiser).
Race wise, I much prefer the old route, to be honest.

But perhaps you are keen on climbing the Saint-Nick. It's your project after all. But I think the St-Nick ruins the race, first because it encourages the riders to a waiting race and second because the St-Nicolas is in downtown Liege, it's kind of ugly and if you are a little bit romantic you'd say that the true Ardennes are no longer promoted. Liege is not in the Ardennes, the Ardennes are the high plateau South of it. Wanne, Stockeu, Haute Levee that is the Ardennes. These are the classic climbs of the race.

Haven't climbed them but many told me that they are the hardest, if only for the fact that they are in succession because of the flat in-between. But even in themselves, they are hard.
The Cotacol Encyclopedia classified the Stockeu has the 2nd hardest climb in Belgium (340pts), the Rosier as 26th (271pts), the Vecquee as 20th (282pts), the Redoute as 36th (249pts). The Saint-Nicolas only has 127 points (rue du Bordelais). The Haute-Levee has 201 points. Wanne has 202pts and the Mont-Theux: 185.
http://www.tcwoensel.nl/clubritten_pdf/Top 25 Cotacol.pdf
http://users.skynet.be/cyclo-wavre/cotacol_belges.pdf
Edit: This diatrics and accent problem is starting to bore me...