Ericus

I have a 1970 Pickup which obviously did not come stock with any sort of anti-theft devices on it. I have spent a few grand on this truck and it has also been in my family since it was bought new. I was wondering hoe successful ignition cut-off switches or things along those lines were at deterring theft, like if they really worked or if it was too easy to bypass the circuitry somehow. Any help would be appreciated.