Despite the progress he had made, few believed that McLean and United were potential Premier Division champions, Alex Ferguson's Aberdeen at that time were an emerging force in addition to the Old Firm. But in 1983, profiting from a late run which left those clubs in their wake, that is precisely what McLean's largely home-grown side did. At this time he additionally acted as assistant manager to Jock Stein with the Scotland national team. Rangers, who had seen a decline in their fortunes over the previous few years, offered McLean the job as their manager in 1983. McLean engaged in early negotiations with the club; one of his main problems with the job offer was Rangers' policy of not signing Roman Catholics, a policy McLean found a ridiculous restriction for any employer as well as having signed many talented Catholics with Dundee United. Despite the Rangers chairman assuring him that this policy would be scrapped if he accepted the job, McLean decided that he was happy at Dundee United; his family were happily settled in the Broughty Ferry area of Dundee. McLean also turned down an offer to manage English club Newcastle United in June 1984. Following his team's League success in 1983, Dundee United made their debut in the European Cup. McLean's counter-attacking tactics paired with a pressuring style brought some memorable results in that year's European campaign. McLean inspired United to the semi-finals of that year's competition, a penalty-kick denying them a place in the final. Three years later McLean took the team to a European final, this time in the UEFA Cup, although they were beaten by IFK Gothenburg of Sweden. For the rest of his managerial career McLean continued to secure United's high standing in domestic football, finishing outside the top four clubs only once, and taking the team to a further five Scottish Cup finals, but without winning the trophy.

Answer this question "What the biggest success of the 1980s?" by extracting the answer from the text above.
But in 1983, profiting from a late run which left those clubs in their wake, that is precisely what McLean's largely home-grown side did.