I might go one step further and say to over build it with quality components and limit the RPM to 5,000-5,500, but 5,500 should be max for reliability.
I think my hydraulic roller cam poops out about 5,600-5,800 RPM and my engine dyno'ed at 605 HP. I think. It's been a while since I reviewed the dyno sheet or driven my car for that matter.
I will say Patrick is right. Zero RPM does wonders for engine longevity.
