Legal question about Antique vehicles and the seat belt laws

I don't live in CA, but according to a friend of mine who lives in San Jose and has antique cars, pre-1964 antique, classic, or other older cars are not required to have seat belts, but California law does not allow a driver or their passengers to drive on the highway without wearing functional seat belts. Also, California law states it is illegal for children under the age of 7 to ride in a vehicle without being properly secured in the backseat. He interprets the first part to mean that if the car does not have seat belts, it cannot be driven on the highway. Anyway, its just an FYI. This is one time a National Standard would be nice, maybe?