i mean no offense by this, but i dont really think you have the know how to use nitrous responsibly. theres quite a bit more to it than slap it on the car, and go fast.
you would probably be alright not having forged internals (crank, pistons) with only a 50 or 75 shot, but i still wouldnt recommend it. what sort of motor is this? a lot of 4 and 6 cylinders will cry uncle on only a 50 or 75 shot.
you would have to back off the timing a few degrees so you dont get detonation when you spray it. you will not be able to spray it under 3000 rpm or so, or kiss your motor goodbye.
assuming you dont blow your motor up, you still have to worry about your transmission and rear end handling the extra power.
knowing the car and motor type would be helpful, but im still going to advise against trying this, coming from someone with some nitrous experience.