There are many many engines with stock bottom ends running over 400+ hp. Many turbo guys run stock bottom ends over 6 psi, 400hp+. I’ve known a stock bottom end 318 in a truck where the guy was running 10 psi for tens of thousands of miles. It’s all in mixture tune, and ignition timing.
How long can you put that much heat and pressure to the combo? That’s to be determined by parts selection, inspector, builder, maintainer, and driver. Obviously if you invest $$$ to the bottom end it will inherently last longer with the new parts. Throwing 400hp at it is no big deal, tho.