I had a 4 cylinder GM Detroit 2 stroke in my barge when I brought it. It was a dirty smelly engine and on start up the smoke was like a fog. The Belgium cyclists used to go past holding there nose’s. Parts are still available but they are a very old technology.
Havent come across a 2 cylinder version but there are 6, v6 and v8’s still running in barges on the continent. They were mostly ex American tank engines but also Allison Chambers used them in tractors.
Very heavy engine mated to an Allison gearbox, when I replaced it with a 6 cylinder Perkins the boat came up 3 inches! Think it would put a narrow boat on the bottom.