The Perkins engine is a little engine that could and it did. There is a reason the Perkins 4107 and 4108 have been in use for so long. They just work. Not pretty. No super chargers. Just 4 cylinders Banging away. Abused. Ignored. Feed them fuel, oil, and a battery charge they ask no questions they just run.
On a boat it is important that the cooling system is working properly Keeping the engine between 155 and 180 F. The alternator needs to be properly charging the batteries. The engine powers smoothly up and down. That engine is not spewing smoke, diesel, or oil out the exhaust. The fuel system is clean. That there are two fuel filters the primary in a place that can be easily checked and changed, and a secondary on the engine. No fuel leaks. No coolant leaks.
When I talked with my fisherman cousin about the Perkins engine he sang the praises of the engine. Said they had a 4107 on a tractor. The tractor had sat for 4-5 years in the corner of a field. It was covered with black berries and gorse. He sent his son with a weed wacker to cut the tractor out of the brambles. Two days later he went down with 2 gallons of diesel, a battery and a quart of oil. Said he fed the tractor fuel, gave it the oil, Hooked the battery up to the starter, then turned the key. It turned over a couple of times and suddenly fired up.
On my sea trial I ran the engine at 60 to 70% till warm then I tested wide open throttle, in both forward and 70% in reverse. I tested emergency stops. All the time watching the RPM, Oil Pressure, and Temp gauges to see how the engine reacted. I also watched the water exhaust for volume as rpm increased and any smoke from such demands.
just a few ideas.
good luck.