Jeff-ro, Think about talking to Ken Reeves at
www.propgods.com (941) 735-5808. He pretty much nailed it the first time for me with the wheels on a pair of 115 E-tec's on an old 9' beam, 5K#, 25 Moppie. He sent me 15" square Merc Enertia's with BRP hubs and said if I wanted something else he would exchange them for $35 each until we got it perfect. 5500 RPMs yields 35mph and still gets 1.6 MPG at WOT. Not too bad for that "tank". I can't imagine what a 23 Seacraft would do with twin 161 shaft HP Etec "150's". Keyword "BallastTanks".
You'll be one of those "Pesky Outboard Fellas", mess'in' with the inboards soon!