I'm sure Chris will chime in, but I don't think his performance with the big block is that much better than a small block. He's got it hitched to a Bravo drive and needs massive Kiekhafer trim tabs to keep her balanced. The biggest down side I've personally witnessed in his boat, and I'm sure he'll concur, is water through the scuppers due to that extra weight. With a couple guys in the back at rest, you've got a good 1" of seawater on deck. Typically I concur with "there's no substitute for cubic inches", but in the case of a 23, it seems to work against you.

The 350 just seems made for the 23; go for that and you'll be more than happy.

It's definitely possible to have too much of a good thing! One friend of ours made the Abaco's trip with me and the "Unohu" in the late 70's in a 23 Sceptre with a 454/No. 2 Mercruiser drive, which was quite heavy because it required a marine transmission between engine and drive. He ran out of gas (with 100 gallon tank) before we got to Cooperstown, a distance of about 130-140 miles! We were headed to Guana Key that year, a distance of about 180 miles, and he was the only boat that couldn't make it non-stop. (I was carrying 80 gallons of gas in the Seafari, over half of it in jugs!) I averaged about 2.8 mpg with the 115 Evinrude and Bob got about 2.5 mpg with the 260 hp/350 Mercruiser in the Moesly 21.

I went with the 350 Marine power carrb 315 HP and love it but when all my friends told me to go Fel injected I have not all the problems they get and cruise at 26-27 and get around 2-2.5 gal per mile. What the heck.

those marine power engines are a very nice package,work very well in an inboard application - i've used a few of them
good warranty too

Yeah, I love the 350 and no doubt that the extra weight of a 454 would be a factor with the thru-deck scuppers(I hate them).
I have that problem with the extra weight from the Yamaha kicker(105 lbs),and the four down riggers,each with 15lb weights,two off the stern,and two off the rear sides.
They drain fine when we are sitting forward or amidships,but if we have two of us standing in the rear,as when fighting and netting a fish,water pours in through them.It's not bad on a hot summer day,but in the spring with water temps in the high 30's forget about wearing sneakers.
I made a version of the "Vortex" out of some 2" long pieces of type m copper tube and the finger from a latex glove.Most of the time they work pretty well."most of the time"not all the time.