How much stress can stock components take?  Particularly stock cast aluminum pistons???  And how many RPM's can stock rods take?????  

When using stock rods and pistons, calculating the amount of life left in them is nearly impossible. There are too many factors that could lead to an early demise. Things like detonation, overheating, and just the overall way the engine has been treated over the years all play a part. If you're rebuilding an engine and wanting to reuse these parts, if properly reconditioned and used in a stock-type of rebuild with an approximate r.p.m. limit of approximately 5,500, the parts MIGHT live for a long time--again, MIGHT. You never know what the engine will be subjected to. If possible, I would replace them using new parts if possible.