I've pushed STOCK bottom ends to MUCH HIGHER power levels than 'experts' have claimed to be the upper limits and NEVER had one suffer damage in THIRTY FIVE YEARS, so I very much doubt that's going to change in your case.
The normal causes of bottom end failure are;
1) Shutting off from high rpm due to lack of damping of the inertia loads stretching the rod and bolts
2) Detonation
NOT actually generating big power figures.
Furthermore, the higher the rpm range you use the higher the inertia loadings on shut off, so its possible to reduce the risk of engine failure by reducing the peak rpm and LUCKILY for you, nitrous will not only allow you to do that while STILL improving performance but you'll actually benefit from using a lower peak rpm, as it produces more torque and even better performance.
One final point to keep in mind, is that the engine is only subjected to peak power forces at peak (or close to peak) rpm, so even if you still pushed to the same peak rpm, as long as you either shut off the nitrous or taper it off in such a way as to prevent the power at any other rpm level being any higher than at peak rpm, even IF 'MAKING' peak power any higher was a problem, you could STILL use nitrous to achieve enhanced performances.