My 49 Dodge was registered using the engine number when I bought it, the original engine was still in it which made things simpler. When I registered the car in my name I was able to change registration to the serial number located inside the drivers door jamb. This was in Indiana don’t know what the situation might be in California. See you have no title could pose a few head aches, it I’m would think you could get a reassigned state issued number.