Technically Title and Registration are two totally different things... all vehicles are required to have a title in the state they will be operated or stored in but you are not required to have it registered except in a few odd cases. In California they have a classification you register the car in where it is not in use... but the Title is required no matter what because it is what shows legal owner. If someone gives you a car and does not transfer the TITLE to the car to you then they could file a police report against you showing they have the title to the car and you have the car and they want it back. Until someone gives you the title signed over to you then someone else legally owns the car no matter how many receipts and contracts and canceled checks etc you have... If the car is permanently stored it doesnt require a registration except in certain states where this is required no matter what. A registration is what gets you license plates and essentially a legal right to have the car on public highways assuming the operator meets licensing requirements themselves as well as carrying proper insurance to operate that vehicle in the state if required.

Your collector should have gotten a title from the dealer (or individual) who sold it unless it is some sort of "salvage" vehicle which would still be reflected on a record of the vehicle somewhere. One of the reasons you are asked for the title to register a vehicle is so that it supposedly makes it harder for car thieves to sell stolen cars... it's what's supposed to stop people from stealing your nice low mileage porsche and selling it to someone else who wants to drive it around...

I believe there is some sort of process where the VIN can be investigated in the state title was last issued in to determine the last recorded owner in that state and then if they can confirm they sold it a duplicate title can be generated in that state and it can be transferred to you. I know in several states I've lived in a duplicate title can be generated and then it can be transferred to you.