The reason you don't see a lot of money invested in stock bore replacement Pistons, is that it is considered a waste of time. Who would go through the expense of disassembling an entire engine and then spend money on new Pistons for a basically tired engine?
If you want to run nitrous on the stock bottom end, and are concerned that you'll blow it up, my recommendation is don't.
Nitrous is a compressive power adder. It creates a lot of explosive force on the piston tops, which tends to hammer things below that. Not so much on the small shot you're talking about, but as nitrous levels get in to the 200-250 range, the bearings and crank start to show signs of that. Added power in any form adds heat to the combustion chamber. In a hypereutectic piston application, it's the difference between how heat gets transferred into the piston versus the top ring where things go bad. As the top ring gets hot from the increased power, it expands. If there isn't sufficient end gap for that expansion to take place, the ring ends butt. They cut the top of the piston off like Marie Antoinette's head.
The other limitation in a hypereutectic piston application, is it don't play. Make a tuning mistake,...have something happen that causes detonation in any instant and the piston could shatter. A forged piston tolerates that much better ( only for a brief second more however) and you might get a chance to lift if you hear the engine rattle. If you don't, a forged piston will fail as well, only it might melt instead of break. A melted piston won't end up as a piece of broken assed junk that gets jammed between the rest of the piston, and the combustion chamber, causing the whole engine to say:
Ka-Blue-eee.
In conclusion for our hyperpiston-entry level nitrous 101 lecture today,
Nitrous systems have been in production since the early 80's. You won't be the first guy running a "power shot" level system on a stock engine. Read up, use good gas, pull out a little timing...pay attention to what the engine tells you.
You'll be fine.
