Migrations usually copy everything as-is: hundreds of courses moved from one LMS or authoring tool to another, including every outdated rule. A migration is the cheapest moment you'll ever have to fix that.
Inventory first
List every course, its format, its owner and its learners. You'll find duplicates, orphans and courses nobody has opened in years.
Retire before you move
Anything without an owner or learners in the last year is a candidate to retire, not migrate.
Link to current sources
For each remaining course, identify the source it should match today. This map is the most valuable artifact of the whole migration.
Flag drift, then fix the riskiest
Check claims against current sources and fix P0 issues before the move. Lower-risk issues can follow in the new system.
Rebuild structurally where it pays
Courses that will change often are worth rebuilding as structured content, so future updates are cheap. See Migration and the Training Drift Audit.