I keep saying this. When I do this, it will be with a Bravo style drive. I already got with Lenco, they have some newer boxes that will work fine for this.
I agree with the 480hp B, nothing better. I'm sure you could juice it up a bit more maybe 525hp and that's it.
Two speed Lenco through the Bravo (style as opposed to big shaft drives) and let it rip.
I need to start with what is a fast hull already, no offense to your boat. If you take a hull that goes 65 mph and now it goes 65 mph with a diesel - who cares?
To make a point with this project providing I can fund it in a few months you need to be in the 80's if not 90's for anyone to even notice it.
I would think with any of the boats that are closer to 30' it maybe be possible to use the 600hp C???
With shifting in the drive and the Lenco weighing almost nothing it's not that heavy. Even a short CV shaft between the drive and the Lenco to move the engine a little further foward will help.
On a side note about CG, there is a thread on here or SOS about best "rough water" boats and it's funny that the experts all list the Buzzi boats as being probably the BEST. Those boats go against what most people do which is move the CG back. The Buzzi boats are very heavy up front, between fuel tanks, ballst tanks and engines.
That's why I think with a little longer boat you could use the C and move it up a little and be just fine, too much on the ass is no good either???