I've always been mystified by the frequent desire to find ownership provenance. To what end? What kind of information would you be looking for? More importantly, just because it came from an owner, how can you verify its accuracy?
I know that my uncle owned my car from late 1969 until his death in 1998, and then I got it a year later. This intimate knowledge brings me no information. We don't know how or why the car, being sold new in New York, ended up as a six month old used car on the lot of a Simca dealer outside of Philadelphia. I don't know what possible information all these years later, that would bring to me. More information was gleaned by the restorer (and me) during the restoration.
Quite a few years ago now, I facilitated the deal between one of my friends, an older woman of German birth in Michigan who owned a 1971 Pagoda bought new, and one of our members here from Poland. The deal took place in Detroit. The member from Poland flew over, I had pre-inspected the car, and brought the two together. Behind closed doors they consummated the sale. But, funny thing: the memory of the owner was tainted. She said it was never crashed, but we discovered upon close examination, evidence of minor body work. She said it had never been repainted, but the overspray in many areas indicated that it had been, at least in part. There were other errors of omission (mechanical) that the seller simply just didn't remember, or her mechanic wasn't straightforward with her about. She thought it was completely, 100% "all original" and it was not.
This is WAY different than the OCD compulsive owner who has records of every fill up on fuel, every bit of service, every receipt and copious photos of the heritage over the decades. The owner here was more typical of any car owner. But over many decades, memory fades and or is distorted. Thus, for example, I'm not sure of what value speaking with an owner of a 230SL, the first in a line of many say, from 1965, would bring you. Maybe some old photos, that's probably the only thing that can be guaranteed to be somewhat accurate.