I think you used standard bus route search with JFK and Heathrow. OpenStreetMap suggests Lisbon since the departure and destination are on different continents, providing a route in close proximity to the destination with access to the sea.
If you prefer the flight path, you can visit dev.sitinshade.com/flight [beta].
If you prefer the flight path, you can visit dev.sitinshade.com/flight [beta].