I don't think there's any cast-in-stone numbers on that. Just opinions. Maybe general consensus is a stock block will live at 600HP. (But my friend's didn't.) Another friend just put together a 600HP with a girdle. Hopefully it will stay together longer.

And what this conversation really brings up is that there really isn't any reason to think about more power these days. Trick this and secret that and all that silly stuff. Just take a stock B/RB block, put in a stroker kit and a Trick Flow top end and you're done. You have 600HP and all the power you will ever want on a stock block. Much easier than the old days when you had to plan on your engine build for a year. This isn't the 70's. We have some great parts to work with now-a-days. Trick Flow heads flow as much (or more) than stock Street Hemi heads. No wonder they make so much power.