The 903 is old tech, very heavy, not very fuel efficient, noisy, and very particular about the chemical status of its coolant.
That said, there are quite a lot of them still in use, many of them original motors in very old boats.
My own favorite thing about them is that the rumble they create underwater is renowned for raising really big Marlin!
You can lead a horse to water,
But you can't make him ski...