He has a title (Texas)
His daughter is trying to register it in California.
The vehicle needs a VIN inspection/verification to register and transfer title. This is the problem.
VIN inspection is required when registering the vehicle.
It is not unique to classic vehicles
I purchased a new vehicle in a neighboring state and needed a vin inspection on a new vehicle.
The VIN has to match the title.
When you purchase a truck for a project it is a good idea to make sure you have a good title and also register it before you invest in restoring it. Once you have it titled AND registered then you can inop it if its not running while restoring it.
Check the rules for your state.
In this case, it may not be a good idea to move the truck to a third state if that state will also require a vin inspection/verification to transfer the title.