MADRID, March 3 : Soccer chiefs from Europe and South America will hold a final meeting before a Thursday deadline to decide whether and where this month's "Finalissima" between Spain and Argentina will be played, with London emerging as the leading candidate after doubts over Doha, multiple sources told Reuters on Tuesday. The match between European champions Spain and Copa America holders Argentina had been scheduled for March 27 at Lusail Stadium in Doha. However, it has become increasingly