This is mythology with no scientific basis, no matter many how many times it’s repeated, or how insistently anyone says it’s ‘nonsense’ to call out this myth. The fact that a lot of people believe something does not make it so.
There is no scientific evidence that dogs called ‘pit bulls’, which isn’t even a breed but just a vague category of appearance, are any more likely to be aggressive to humans than dogs of other appearances, or attack more ‘viciously’ than other dogs the same size, or any other systematic difference independently of how they are managed by humans.
If you have to deal with strange dogs and they seem aggressive, you should go with your instinct and be careful. And assuming the situation justifies it, the good news from OP perspective is that there’s also zero basis to think a 60lb ‘pit bull’ would be any more resistant to a stun gun, bear spray, a club or whatever else than a 60lb dog of the same temperament, size and physique but different appearance (of course 60 lb dogs have more potential to harm than 20lb dogs in general, and 60lb fit dogs more than 60lb obese dogs, but there’s no systematic difference in ‘pit bull’ appearance type dogs otherwise physically compared to various other types of dog, the idea that their jaws or teeth are unique is another wive’s tale).