Having recently done this upgrade to HPK, couldn't agree more. This is my recommendation if on track plus GOOD pads. Don't put shit pads in with good discs...pointless exercise.
I used the SC pads too, but I've been offered a part worn set of Z04s to try so gonna try them next as everyone says they're also another level. Costly consumable though so I'd want to notice a big change in performance.
ive got z04 pads in my track bike, they are good, but tbh i cant really tell the difference between them and the sc pads. maybe im not riding fast enough