Complex sentence: The original plan for the upper level (now the) to continue as a two-track line along the LIRR Atlantic Branch would have run through Locust Manor and Laurelton stations, with stops at Sutphin, Parsons, Linden, Baisley, and Springfield Boulevards.
Split into simpler sentences: The original plan for the upper level (now the) was for it to continue as a two-track line along the LIRR Atlantic Branch. It would have run through Locust Manor and Laurelton stations, with stops at Sutphin, Parsons, Linden, Baisley, and Springfield Boulevards.