So I've been trying to see if I can figure out the PC kit to fit the plastics to my bike. It looks like they used parts from the KX250F, judging from the gas tank that has two outward facing bolts on the tank. The 450 tank has a downward facing bolt at the front:
The sub frame looks to be a pretty close fit, bolting up on the left side (judging from the distance from the exhaust mount to the frame mount on the subframe, it looks to be the same from the 250F and the 125), and requiring a pretty simple looking bracket on the right:
I'm not sure if the tank fits without modification, but it must be pretty easy as it looks to fit really well. The airbox would be simple, just using the stock two stroke stuff and a blank plate fit over the box.
I think you would have to adapt the radiator louvers from the 250F to mount the shrouds, but I can't really see. Does anyone have a 2017 250F to take a picture of how the shrouds mount?