I recently got two bikes with original title in hand but since they were out of the system (DMV seems to purge after a few years) I had to get a new title. I was happy for this because it meant re-titling and no back fees (both about 20 years so it would be fairly expensive).
To get a new title for them I had to bring the bike and have the VIN and engine number verified. On the Suzukis there is a number stamped into the frame and also a foil sticker which had, as usual, been worn down by the cables, but the numbers were still visible. It seems the stamped numbers should be enough as I've registered older bikes this way without one, but they looked at both. I had to trailer them in as they were just engine and frame, and brought plate and speedometer too. You may need to bring your bike there.
Line wasn't bad, took 2 hours to get it all done.
I asked about an old Norton that I have only a bill of sale for, and the guy said sure, bring it in and in addition to verifying the VIN they will need a 'statement of facts' from the seller or last owner, certifying that there is no lien on the bike. You may need to do this step, just passing on what I have dealt with. Good luck.
The CA DMV can clearly see in the national system that I'm the registered owner, so why can't they just title and register it for me here? I think I need to bite the bullet and waste a day trying to get DMV services in the age of COVID.