I have a 1975 Pearson 28 sailboat with an Atomic IV. I've had the boat since 1987 and don't really know how many hours are on the engine. We sail it on LI Sound and it is raw water cooled. We have hauled the engine out twice using the main halyard and boom yang. I would expect that 1182 hours is not much for a 1975 engine. Doing the math that works out to less than 50 hours per year. I guess that if properly maintained you could get another 10 seasons out of it.
Regarding gas vs diesel, diesel is safer but if you sniff for gasoline before starting and run the blower before and while using the engine, you should have no problem with the gasoline engine.