Finding older vehicle history can be a downright pain. Many states are enacting driver privacy laws nowdays due to the number of wacko people out there. This can lead to all sorts of problems finding previous owners. For example, just after I researched my 81 Florida enacted a privacy law(at least I think they did, I filled out a form anyway). Florida kept records for only 12 years then the old ones were destroyed, I just happened to get lucky and the last person on the history report was the second owner who told me he couldn't remember the original owners name but he owned an isulation business back then. I ended up calling ALL the insulation businesses and telling the receptionists my crazy story, finally the last place on my list turned out to be the guys brother. He called me back later that day and told me to come down in a few days, verified the car and gave me all the original paperwork including all the sale documents. Turns out he lives next door to my boss.
If you persist you can find anyone, just think creative, sometimes you can find a DMV employee that understands about old cars. Sometimes if you find out who owned it before you they can help get you in the right direction.