Cyclesmakaron, I promised a report back after the weekend.
I’m afraid it may not be terribly helpful.
The bike I bought, Z 1701 was one of two Merckx’s two brothers bought (as mentioned before).
The brothers spoke this weekend and I got to speak to the second brother.
He does have his bike still as well and I am going to see it Wednesday.
In conversation today this second brother confirmed to me they bought their bikes in 1984 and his brother raced his 9/84.
He remembers the race, the announcer, all of it, just as the first brother told me.

I asked if he has any records though and he does not.
I asked how he recalls it was 1984 vs 1985.

He told me a very significant event happened in his life that year which he will never forget.
He told me what it was. I cannot share it. It is not my right to do so.

Clearly this is not ironclad evidence but it is strong.
If I find out more when I meet him Wednesday I will let you know.

I do not mean to muddy the waters of your factual research.
Two brothers could surely convince each other of the year of an event 36 or 37 years ago.
The fact they both recall the year for different reasons is reasonably strong to me but it’s not a sales receipt.

Without bias either way I am simply telling you what I have been told.