Re: carbon fiber VS glass
Putting carbon fiber on the inside of an old hull won't do anything for you.
The advantages of carbon fiber are high strength and low weight... if you already have a poly and E glass hull, you're not getting the weight, and if you're only using one layer of carbon on the inside you're not getting the strength, either. You'll get even less if you're not gutting the hull out and laminating the carbon, then rebuilding the interior structure.
It sounds kind of like you want the look of carbon fiber on the inside? If that's so you need to think it over some more... you have to use epoxy to laminate carbon fiber, but boat epoxy is UV sensitive, so you have to paint over it to prevent yellowing. So you wouldn't see it.
"Big horsepower" isn't clear, but I'm guessing you want to exceed the max HP the boat's rated for. Legal and safety reasons aside, this won't get you all you think it will.
The boat's hull is designed for a specific horsepower, IE the difference between a 100 HP boat and a 300 HP boat is more than the strength of the hull and transom. The hull is shaped to perform a certain way with a certain amount of power behind it. Adding a lot more power will get you more speed in a straight line, but it likely will also make the boat unsteerable and unstable (read: likely to have a bad accident).
If you really want to do this, I'd suggest you scratch build a hull to the shape you want, make it a composite hull with two to three layers of carbon on the outside and the same on the inside and a strong transom.
If you want to rebuild the century to be custom, I'd go with a different angle, maybe looks and comfort. Redo the interior with snap out carpet, plush seats, a refrigerator, sound system, etc. Put in sound proofing to make it a quiet, smooth ride.
If you want to go the high HP route, don't bother putting in carbon inside the hull, it won't do anything for you except let you say "my boat has carbon fiber in it". Just put the big engine on it and be aware you're risking a lot by doing so.
Erik