Yes, the geopolitical situation with the Cold War helped Northern Europe. But don't underestimate the vast amounts of money the EU has invested in Spain and Portugal since the 1970s.
Lots of money yes, but not that well invested. Scratch the surface of EU funding and you find a long procession of malinvestment and wasted opportunity. Airports being a famous case in point:
Portugal did receive help from the Marshall Plan. Not much (70 million, only Iceland received less at 43 million), but it got it
Well, Portugal and Spain were not really affected by the war. They were, however, affected by the isolationist dictatorships that they had to suffer under for another 30 years.
Let me remind you of the Spanish Civil War of 1936-1939, and its hefty toll on Spain. Like all civil wars, it never really ended.