Nitrous on a 318.....how much will it take

A ferfegneugen LOT. One of the hot rod rags did a story on a total junkyard 360. They literally snatched it out of a junk yard, threw a four barrel on it, headers, got it running and TRIED to blow it up with nitrous. They never did. I think they ended up with a 300 shot in it. It kept runnin outta valve spring. LOL