The factory paint on these cars was terribly thin and even somewhat missing in some inner areas (like old Fiats), it also did not age well in the sun and would chip very easily - Its shine was sub-par too.
Compared to a similar year toyota cressida or mazda 626 etc whose paint was super nice. Currently Toyota recommends sikkens for all refinish jobs but I do not know what they did recommend back then.
For a good paint system, Glasurit, Standox, Sikkens etc are excellent - provided that your painter actually follows correct technique and uses the entire system from start to finish. That means using their primer, adhesion builders and flex agents for the plastic parts. Most painters use super cheap bad quality stuff for primers etc.