Complex sentence: The Penske team chose to miss Italy, returning for the United States Grand Prix, abandoning the March 751 in favour of the new PC3 with Northern Irish driver John Watson.
Split into simpler sentences: The Penske team chose to miss the Italian Grand Prix, returning for the United States Grand Prix. For this race the March 751 was abandoned in favour of the team's newly-developed PC3 driven by Northern Irish driver John Watson.