Car title

If it has no VIN at all, and you replaced the dash with another with a VIN tag on it, and have some paperwork for that VIN, why not just register it under that VIN? It will get you a plate that allows you to drive the car, and would probably never be questioned. Unless it’s a high dollar car that would be scrutinized, I doubt anyone would even care. Legal or not, it is a car with a VIN, registered that way, and would be in your name.