Complex sentence: It was to have seated 44,130 and would have been a modernized replica of the current Fenway Park, with the same field dimensions except for a shorter right field and reduced foul territory.
Split into simpler sentences: It was to have seated 44,130 and would have basically been a modernized replica of the old Fenway. It would have seated 44,130 and have the same dimensions as the old park, except for a shorter right field and reduced foul territory.