State Farm doesn't write many motorcycle policies so the agent you talked to probably dosen't know much. Most engine modifications we do on vintage bikes would not void your insurance as they could be considerd as repairs , example : you can't buy stock carbs for an XS, they don't make them anymore so a set of VMs is ok because they are street legal. You might get into trouble trying to claim loss on a set of Lectrons because they are not. Insurance companies are more concerned with safety features like brakes, lights , tires , suspension . Most mechanics will not safety a bike that has been bobbed/ chopped or any other frame modification or if the factory safety features have been removed . It is ok to upgrade , like putting on Brembo brakes , but not ok to remove the front brake . This info is for Ontario Canada , but may apply to other locations . Better off making sure you can make your project road legal before you take a grinder to it.