In some states as long as the vehicle is 25 years old and older you can register the car without a title.
So in most states you do not need a title for an antique car to get it registered in your name as an antique.
All you need to register an antique car or other antique vehicle in your name is the bill of sale if you just purchased the vehicle.
You can also go to a title company who can help you legally get a title for the antique vehicle if you need one.
But usually the bill of sale will work to register the antique vehicle or antique car in your name.
One you get the antique car tag then you usually only need to pay the property taxes and not need to pay the yearly registration fee.