[Fr. Frank]

Originally Posted by SnafuFishTeam

1. Max HP on a 23' cc was 400 hp.

Not necessarily. It depends upon the year. I have rigged quite a few 23's with an original placard that said "Max HP=500. True, most got single 235's. Some got twins from t/115's, to t/235.
And I have owned two such rated hulls myself. 1st one a '77 23' SF, originally rigged with '78 T/235 Evinrudes. 2nd one a '78 23' Savage, rigged with twin Merc 225's. (Yes, the Savage with the Mercs was faster WOT than the Evinrudes by all of 2 mph). Here's the Savage specs:
http://www.classicseacraft.com/Savage23.htm

AND just for the record, the 1983 23' SeaVette with the transom cutout for twins was available placarded for 600 max OB hp.
We sold one at Waterway Marina in late 1983, and then sent across the street to Frank Brown's for rigging and motors. He rigged it with twin big-block 300 ELPT Mercury motors, that reportedly topped out at 77 mph after playing with motor height, props, and after installing nose cones. This VDH thing is for real!