John, you and I are on exactly the same page regarding engine power and weight! Based on Terry's info, I think the 90 E-TEC would do exactly what you want, but here's another relevant data point: I ran my Seafari for 31 years with a 300 lb 1975 115 V-4 (rated at powerhead) on the transom, which probably developed just about the same power at the prop as Terry's 90 E-TEC, although it was a 100 cu. in. powerhead, so it may have had a bit more mid-range torque. Although the bare hull of the Seafari weighs 1800 lbs, vs 1400 for the CC and 1300 for the 19' Bowrider, it rode VERY well, planing at about 12 mph, and cruising at about 20 kts @ 4500 rpm with a very heavy Bahamas-type load (ran it over to Green Turtle, Gt. Guana and Man-O'War Cays in the Abaco's a half dozen times back in the late 70's/early 80's).
On one trip with large following seas, I learned that there's an advantage to having a small motor wound up pretty tight. At 4500, when I started "uphill" on a swell, I found it starting to fall off plane, so I bumped the throttle up to 4600-4700, and problem solved, no more throttle jockeying required! It would easily hold plane going uphill, since peak torque occurred at maybe 47-4800! One time with the motor off, I had someone move and mark the control lever while I watched the throttle & spark advance linkage. I discovered that for about the first 75% or so of throttle travel, all it did was advance the spark;the throttle plates barely moved! The throttle plates opened almost 90 degrees during that last 25% of control travel, and they were just beginning to move at a typical 4500 rpm cruise setting. When I got up to around 47-4800 the motor got much louder (visualize a toilet flushing as all 4 carbs started to open up!), accompanied by a similar increase in torque!
When I repowered with a much heavier motor on a bracket, the effects on ride and min planing speed of the shifted CG, which I think moved aft about 18", were dramatic and quite negative! (The details are described in my "Pros & Cons of Brackets" thread.) With the 427 lb "150" E-TEC (165 HP at prop) on a 30" bracket, optimum cruise is at 37-3800 and about 23-24 kts and 7 gph. In 3' seas, the boat will be airborne about half the time at that speed, so I'd have to slow down to about 20 kts! That's down around 31-3200 rpm, and although the motor actually gets the best fuel economy at that speed in flat water, it's clearly on a very steep part of the torque curve at that point, because speed is not very stable. When trimmed for max economy at ~20 kts, even a slight wind gust or wake will cause it to start slowing down, so much throttle jockeying is required to hold a steady speed unless I change engine trim or tab setting. If it gets rough, I can drop the tabs and trim motor down and ride very comfortably sitting down 8' fwd of transom in 3' seas at about 12 kts, but fuel economy REALLY drops off! In that situation, I think a 90 hp motor wound up higher on it's torque curve with a larger (more thermodynamically efficient) throttle opening would burn less fuel and require less throttle jockeying than a bigger motor.
The 19 & 20' hulls are virtually identical below the chines, since Moesly modified a 19' mold to make the 20 (see Carla's website at
http://www.moeslyseacraft.com/20-cc-seacraft.html), so Terry's performance numbers would apply equally to a 20. If you add a bracket, I would minimize the setback (Don Herman can build his with 18, 24 or 30" of setback), and try to move the gas tank and console far enough forward to keep from moving the CG. Couldn't do that in the Seafari, so I've had to run a 4B prop and a Doelfin to get enough stern lift for acceptable min planing speed. The extra drag of those items have knocked about 10 mph off my WOT speed, so, although I love the bracket for diving, the extra space it provides and the safety of the solid transom, the performance improvement claims of a bracket are very misleading and way overblown IMHO!
You could also consider the new 90 HO, which is actually a detuned 115 V-4 with a V-6 lower unit and a 2.25:1 gear ratio instead of the 2.0:1 of the 90. It's 105 cu. in. vs 79 cubes on the 90 so it'd be a torque monster! Probably cheaper than a 115, but also MUCH (70 lbs!) heavier than a 90, so you'd be better balanced with the 90. Good luck with your decision! I probably haven't made it any easier! Denny