KH disks to 5x4.5

I have to say, I can't see it being worthwhile to try to jerry-rig a rotor for this app. Rotors are expendable items (especially for the K-H brakes) -- you go to all this hassle now, you'll have to do it all again in ten years (assuming you drive the car regularly), and you'll have to search out all new vendors. I would just do aftermarket brakes, or switch to BBP sliders. That way you won't be at the mercy of customized parts.