Personally never was thrilled with the ride of a single engine islander. Fished a few and they did the job, but were on the slow end, and the guys I know who had them all had blown engines before 1000 hr because the boat is slightly underpowered, if your going to be pushing a family around you want enough power to not be running the engines hard to handle the load. The single engine 2 stroke boats were ok, but remember most of the newer 4 strokes do not have the same pep and weigh more, making them less ideal. If you could find an islander repowered with a 300 suzuki or F350, that would be a different story, but I do not think an F350 would fit on the islander, cowling is too high to tilt up, and transom mount I believe is different as well. The Suzuki would be a nice power match with good economy though and enough power. The 258 will be easier to find with a single and will handle the power of a single a lot better and ride better, making it the best option on your list and much easier to find then an islander with the right engine.