I plan on it! I was just wanting to know what to expect.

I have a slightly different opinion... Hulls are designed with a potential, considering speed and HP. If you exceed the capabilities of the design, you're asking for trouble. I have personally seen the results of too much horsepower in a boat that wasn't designed for it. It sounds like you've already made up your mind on what to do with the boat. If you do add that much power to the boat.....Well, just inspect it very closely after each hard pass in rough water. It's not the glassy smooth water  that I worry about , it's the rough. All boats flex and change shape in the water, and it is exxagerated in rough water. Now, add horsepower and there could be  an issue. Look for signs of stress between the seating area and the leading edge of the stringer. This is where I believe you WILL have problems. It may not be this year or even next year, but it will occur.

     The other option is to take the money being spent on the motor, and put it towards a hull that has the potential to do what you want. Upgrade the motor later on when money permits, and then you don't have any question on hull integrity.

Had I been working there when your boat was built I would have given you my opinion. I left Tahiti in 1974, I have no fuking idea what was going on there when I was at another shop. 

By the way, this motor box you guys keep talking about, doesn't do jack shit. The idea of full stringers, in a jet, is to spread the load, or the strain, over the length of the bottom. Stubby stringers won't do this, but depending on the lamination schedule (the amount of glass UNDER the stringers, among other things) this could or could not be a problem. My dads old Hawaiian had stubby stringers, extremely nice lay-up, for a Hawaiian, had a healthy BBC and would run 72-74 mph. No flex, no hook, no distortion. Would have full stringers made a difference, probably not for his purposes. Do bottoms flex on a boat with stubby stringers, yes, 48 inches in front of the transom...where they end. Any hook that might already be in place is exaggerated at speed, the faster you go, the worse it gets.

You could build a 'motor box' that came up as high as the gunales and the bottom would still flex at the same spot.

And full-length strings don't always mean 'quality'. The reason some Hawaiian's have them isn't because of any high performance goals. It was because the laminators began to leave out some of the layers of glass because one of the company owners decided they were making too much money. So they lowered their pay. We were all piece work then, so as you can imagine this pissed off quite of few guys. To retaliate, they just left a bunch of glass out. We had hundreds of boats come back with the bottom falling out to be repair under warranty. We had 2 full time guys that did nothing, for years, but fix bottoms. The full stringers were a band-aid fix, but of course were used as a selling tool.
All shops have the same horror stories...you just don't really want to hear them. lol