I saw a sceptre with the same Galley set up as your boat and it did have a plastic fresh water tank installed under galley however I don't know if that was an owner modification or factory installation.
Nice boat bye the way...I've been eyeballing it for over a week now. I have a 25 Seafari awaiting restoration and the more I see how nice your boat looks sitting in the water the more it makes me want to start working on it.
You mentioned twins earlier. I posted some pictures a while back of an old 25 that was in the Bahamas and it had twins on a gill brackets. The 25 was originally designed for a IO and is best probably left an IO but you can probably make twins work if you were to move the fuel tank as far forward as possible.
Forum member "BigFluke" in Honolulu has three 25 Seafaris...one of which he is using as a test boat for his research on deep V designs. According to him the 25 has better "sea keeping" ability then the 23
The 25 was discussed on this forum a while back and it was how should I say......a hot topic
Moesley designed and Potter built as far as I see it you cant go wrong with a 25 Seafari.
strick