Or you run into one of the many DMV workers who don't interpret the rules the same way the person on the phone does.... I swear getting the same answer twice is virtually impossible... And when those answers relate to old cars & vintage plates getting the same answer twice is far worse....
California now has a program to allow old plates but they don't care what those plates came from just that you give them $$$$... Likely any attempt to get your plates back on the car will be pushed toward that program...