California is the problem for you. That vehicle needs to be a federal or California emissions spec vehicle. You try to register in CA, car will be required to visit Smog Check Referee. Referee will look for emissions certification label and if meets USEPA (ferderal) or CA, car will be allowed to register. GM may be able to provide a Certificate of Conformity or Referee may know. If not it goes back to Canada.
Another possibility is Gray Market Certification Lab, but really expensive. Plus a bond must be put up to assure the the conversion status of a gray market vehicle (if not, the feds can confiscate and destroy and they don't care. Someone once tried to import a Porsche 959 carbon fiber without a bond and vehicle was crushed). And the lab may choose to accept your vehicle or not.
The direct import regulations are very strict and CA has it's own set of regulations when it comes to Gray Market vehicles.