Care to point to one of those 1000 HP engines you've actually seen? One that is in no danger of blowing the heads off?
Because all I see are a few claims specific to drag racing. A sport known for engines that run just long enough to make a 1/4 mile and occasionally exploding spectacularly. Mysteriously, none of those claims included any actual measurement or documentation.
There are many engines adaptable to aviation. Many good engines. But if the concern is having something at least as capable as the original Bugatti designed engines, you're talking about an effort that will exceed that of the rest of the plane (including the engines they did choose) in both time and money. It can be done, but you're not going to get there buying an off the shelf automotive engine and turning a few mixture screws. Instead, it will involve a great deal of designing, machining, and testing.
Remember, engine failure in an airplane is an emergency. Engine failure with parts flying out stands a great chance of being fatal (and not necessarily just to the pilot) even moreso when the engines are in the body of the plane rather than the nose.
But whatever, build your own replica and power it with a beefed up Briggs and Stratton running on liquid schwartz. I'd love to see it.