The only safety switch on a mower that is really needed is the seat switch.
And there has never been one that is not able to be replaced.
While the smplicity branded one might be NLA there will be an aftermarket one that will work.
The manual PTO switch is a standard long lever micro switch available from any electrical parts store for under $ 5
The gear box neutral switch is also available but usually all they need is a clean out.
OTOH if you are hell bent on making your mower dangerous then go look at what the shaved monkeys on U Tube have to offer.
Lots of clowns there demonstrating their "superiour interlect ' by showing how to do what 12 year olds are taught in school
