Wanting 500 hp (or close) out of a stock stroke 360

I'm running a stock stroke 360 with 534 hp (my engine builder let me know that a few days after it was dynoed they discovered a calibration error on the dyno. Applying a correction factor puts it at 555hp. But since I have a dyno sheet that says 534, that's what I will report)

As I see it, the differences between mine and yours are, my heads have Stage 3 CNC port (flow 303, 222 at .650) and intake ported to match. My cam is solid but with similar specs. My compression ratio 10.6. Fast EFI. Not sure about the rotating assembly differences but I know Mike prides himself on this.

I'm not sure where you are hp-wise, but I would suggest doing full port of the heads.