When selling, separate verified facts, reported history and uncertainty
A strong vintage listing does not need to read like an absolute expert certificate. It should make the confidence level of each statement clear.
You can distinguish between directly verified, documented by receipts or photographs, reported by a previous owner, and unverified.
List modifications, repairs, refinishing, replaced parts and retained original components. If dating is approximate, use a range rather than inventing an exact year.
Transparency reduces disputes and makes the positive aspects of the item more credible as well.