There are a LOT of 500hp 350's out there. This isn't anything new, and it doesn't need to be as radical as people are describing, though it is expensive.
You can get there with a hydraulic roller cam, flat top pistons, 200-220cc heads, carb or efi, nothing too extreme. Realistically you're probably looking at a power peak around 6500 rpm, which is higher than most street driven cars but not too unusual. A higher stall would be needed as already noted but a manual trans would probably be best.