Thanks for the encouraging comments. With the help of rszmjt and tomstiel I have pieced together a brief history from 2000. Unfortunately, the Protectoplate, California 1968 license plate and the Harry Mann Chev license plate frame have long since disappeared. Probably in the trash and now a land fill somewhere. But this car deserves a documentation package so from info on this forum and the Camaro Research Group, I will endeavour to find out what I can.
Happy driving and be safe.