It seems our friends from across the pond have a high availability of small diesel engines.
About a decade ago it was easy to go to almost any hardware store and buy a generator, air compressor, welder, etc that was diesel powered. It seemed with the ultra low sulfur diesel fuel those all dried up except for some small tractors and farm equipment. Its one thing to buy a generator for 500 bucks just for the diesel engine, its another to pay 15 grand for a small tractor for the engine.
600ccs? Sounds like the 19 hp kohler engine from my lawnmower would be a good fit.