That seems ridiculous that you should have to mention that 43 years later. I could see 7 years, but that would be it if not too many years.
A friend had his NEXUS pass (the Canada/US equivalent) pulled because he had failed to mention a 28-year-old conviction for punching a guy in a hockey match. No damage was done, but it was technically battery. He paid no fine and was released on good behavior. They also put negative comments on his file so that he was held up around an hour each time he crossed the border. He spent countless hours getting it straightened out. A INS officer at the border eventually helped him out and deleted the negative comments. He still hasn't got his NEXUS pass back.
Contrast this with the kid-glove treatment given those likely to do us harm.