Numbers you can plan around.

The opening move is to find out whether the audience exists at all. Columns are standardised to one definition each, and the original kept beside it. If a requirement had no countable equivalent, the nearest one is named.

Hand-off

Delivered in the format your systems take, with the field definitions written down.

Correction

Updating what has changed, wherever a current value can be established.

Scope agreement

Turning a written requirement into countable criteria, and confirming the size before any records are assembled.

If it turns out your existing data is fine, that is a perfectly good outcome.