Do some searches about motors in X-stars. We've discussed these motors a lot. We've had 2 big block X-stars and 2 LY6 boats. The LY6's get the job done at sea level, but struggle when heavily weighted at anything over 3k feet. By heavily weighted I mean at least 2500lbs+people. That's with a reprop. The LY6 will get the job done, but you'll have nothing to spare. The 8.1 is a monster. We had reliability issues with ours, but the motors are amazing power wise.
That said, you may have a different experience with a X35, but the X-star is a very inefficient hull design. The wake is amazing, but they require a ton of power to make it happen.
We're going with a Malibu LSV for this season and have spec'd it with the 6.0. In that hull is should be plenty with their optional high altitude prop.