Not exactly an apples to apples comparison here... but I've got a 2004 Grady White 228 Seafarer with a single F225 on her, and I definitely wouldn't want to go with anything less in terms of horsepower. My boat will hit about 42-43 mph @ WOT around 6k rpm, while being roughly half full of fuel and weighing in at right around 5,300 lbs. Comparatively, a 232 Gulfstream has a dry weight of around 500 lbs more, 4,025 lbs for a single engine 232 Gulfstream, and 3,510 lbs for the 228 Seafarer, along with the 232 Gulfstream having a beam of 9'3" as opposed to an 8' beam like I've got on my 228 Seafarer. Between the wider beam and the extra weight of the 232 Gulfstream, I think you'd definitely be wanting more horsepower, and while you could go with a single outboard on a 232 Gulfstream, I don't think the 225 is the winner. Something like a single 300-350+ hp outboard would be much better imo, or as you mentioned twin 150's/200's if you're specifically looking for something with twins on it. Just my thoughts on the matter, of course. If you're really interested in the boat, take it out for a sea trial run and see what you think.