Another Police Equipment Question?

As you can probobly tell by now, I don't actually own my own car yet, but to add to my last question, If I did get an antique police car would it be legal to put a light and siren and police decals on it as long as it was clearly outdated? I'm talking about taking a 58 ford fairlane and doing a seni-complete to complete restoration, making it look like an antique police car. The 58 Fords have to be the most beautiful police cars ever made.