Hi @david.hahn1,
display_in_search will be set to -1 in under these conditions:
0. In case of a temporary entry that was used for entry replacement.
1. In the event a parent entry ID is defined and this entry shouldn't return in lists as a stand alone entry.
Last week we also added code that exposes this property in the API but it will be a while until that makes it into the stable version and CE 5 certainly did not have that.
At any rate, for your purposes, you can safely ignore all entries with status <> 2 when migrating.