How much HP or Rpm can a stock bottom end with stand

There's a lot of variables. The crank, the machining of the block and crank, the balancing, the weight of the parts, the type of power being produced, the fuel... It all factors into longevity. Anything you can do to make the machining more precise, the balancing specs tighter, and the parts lighter will all go a long way to add life span. Typically, assuming the rotating parts are of decent quality, the main caps move first. Then the caps themselves deform. Then the block fails. Adding extra cap bolts simply adds stress to the block - it won't solve any cap or power issues. Girdles won't address the block issue either. So once the expected power output reaches a certain "critical mass", you should upgrade to a better block. The opinions on what that critical mass is vary greatly - so talk to your machinist. Ultimately it's your money and his warranty & experience you're paying for.