nitrous

i have a stock motor i want to throw nitrous into. what is the safest but biggest shot you can put on it with out blowing it

That a hard question to answer.
It all depends on the condition of your engine, and what type of setup you plan on using.
There is the dry setup and of course the wet setup.
I know of a few people that have been spraying a wet 75 shot for the past 2 years and another for about 3 and a half years now.
I sprayed my high compression B17A1 for about a year on and off.
I wouldn’t recommend anything over a wet 75 shot for a stock motor.
That would leave you a nice safety margin. I would suggest that you get the Hondata s100…to tune, they are pretty cheap now.