2000 yz125 top end death rattle...assessment-help

[Samcwach]

So i went riding today, bike was running great. Noticed a substantial top end rattle, and a loss of power. Bike ran and rode out of the trails. Pulled it apart. It's got an Athena big bore kit and cylinder. Piston was scored by I believe the power valve. Cylinder fared pretty well. Rod has no up and down movement. The wrist pin and bearing was very sloppy when the jug was taken off. Took the piston off. I have some questions about the power valve, pics may help. There are wear marks on the power valve parts(see pics) so what next? Obliviously a new piston and cylinder honing. I've never taken apart a power band before, I want to make sure it isn't just gonna hit the new piston and ruin it.