I have a 94 226seafarer and upgraded a few years ago. Make sure your transom can hold the weight, have a mechanic check it out for you with moisture meter and they can put stress on it. Unless you go with one that is post 2012 I believe, the 4 strokes are about 100-125 pounds more than a 2 stroke. They trimmed a lot of the weight don in 12 I think. A good test is have someone who weighs around 100 stand close to engine and see how it sits in the water with the extra weight.
I went from a 2000 225 optimax to a yamaha 2008 225 4 stroke. 95 pound difference if I recall. Extra HP balanced extra weight speed wise. My boat did sit about 2" lower in rear though. I used the ball scuppers to offset that problem a bit, but they need attention, barnacles grow in there.
This year, I took my 96 gallon main tank out and replaced it with a 56 gallon upfront where it was plumbed for the auxiliary 56 gallon tank. (plenty of range for me). BIG difference in the weight distribution and she sits much better now in the water. I feel 1000 times more comfortable now. FYI-I had a storage box made 63"LX18"WX20"D made to fit into where the old tank was, storage is not such a problem anymore and a much less cluttered deck.
