The Eminger report is one of the copies of the actual invoice sent along with the car when delivered by Motor Convoy to the Dealer. They list all the standard equipment and production installed options. The invoice included retail, dealer cost, shipping, holdback, X Y Z D purchase plan prices, and several other categories. It enabled the Dealer to get the vehicle inventoried and into their accounting system. I have also seen some of them on newer models with the FA and FB key codes. If it isn't on the invoice, it didn't leave the assembly plant with it. Since the Eminger/Ford invoice is an original Ford document, I would consider it one of the most accurate reports to have on your vehicle.
Accessories were the Cash Cow for Dealers and aftermarket installers (and still is now). So a lot of Ford and aftermarket items found their way onto our four-wheel friends. If installed before sold, dealers would add an Addendum label listing items added to the vehicle since it was against federal law to alter the original window or Monroney Sticker. Another reason for having the original Ford invoice is how many items are claimed as original production installed by non-original owners when they were Dealer installed. Without a verifying document such as the Ford invoice, it's a "He said, She said" argument. I have several of them for my vehicles, so they are excellent reports to have.
As far as tracking down the original owner, that is no longer an easy task. As a second owner, I was fortunate to have been able to talk to both original owners of my two money pits. It's probably safe to say that many selling dealers are no longer in business, changed owners (several times), or changed locations. As dealers transitioned to computers in the 70s and 80s, mountains of paperwork were discarded. I know the policy where I was at was to keep the deal jackets for 5-7 years and shred them since they contained personal and financial information. With the privacy laws, obtaining any information from the DMV, courthouse tax records, etc., is next to impossible. For entertainment purposes, you could try your DMV or the Dealer listed on the Marti report. It doesn't cost anything for them to tell you NO!!