Great information. Thank you Mastiff107 for the link to your plate-man's Old License Farm, looks like he does good work.
I so love how our bureaucracy always has such diversity in answers. I talked to DOL earlier this week and was told it's kind of fuzzy in the level of details DOL have for the restored plates. My DOL guy seemed to be quite fluent in the restored plate process, and claimed that the WA DOL really have no way to verify the plate as authentic. Sounded like the data on many of the old original plates registration records are unavailable.
So he says all they have to go by to authenticate the plate is by matching the plate numbers to the DOL's county-coded records of plates produced county by county during the plates production lifetime. Ian Slade has done a fantastic job at documenting the Washington County-Coded Passenger Plates, 1958-1981 at this link to his web site:
http://staff.washington.edu/islade/counties/index.htm
He went on to inform me that if the numbers match recorded county-codes on record, the final DOL decision is made based on the colors of the plate matching the era of the car you are registering the restored plate on.
I asked about using reproduction plates (although prohibited by the WA DOL documentation I have read), and basically he indicated a reproduction plate with the correct numbers and colors which is not recorded as currently registered, will pass the DOL criteria and be allowed.
Thanks everyone for your valuable input, the hunt begins!
Regards,
BC Kevin