Take a SEPTA or other local train to Trenton, New Jersey. Take a NJ transit train to Penn Station in New York. The train runs between Trenton and NY roughly every hour. You *may* have to take a local train to Philly first, but I am not positive. (I do not know which local trains run through Flourtown) Call SEPTA 215-580-7800 TRAIN! is the fastest way, even on the train you are going to travel at least 2 hours each way.
SEPTA website has a trip planner, where you can put in a start address, end address, and it will produce multiple ways of getting there.
Have a great trip!