Turbo Doc would be your best bet. You could see if someone would custom build. I am sure you could talk a few guys into it. Other than that it's finding a used one.
That is one of the best motors on the planet, to turbo.
Have a 2006 CMX with a turbo doc aerocharger on it that is ready to go. Sell the whole sled cheap. $3500. Sled hood and seat are rough, but starts and runs on first pull. Polaris 800 power plant. 162x16 track