It looks like published database has had its transaction log restored past what was logged in the distribution db. There is a gap in LSN's preventing the logreader from starting as the log has been cleared of that LSN so it is now in the "future".

Its been a significant amount of time since this issue occurred, I suspect you may have take it on the chin now and consider alternatives. Initially though, you need to get replication up and running on production and that involves loosing those transactions.

You will need a plan on how to synchronise the data on the subscriber in someway.

Perhaps consider setting up a logship from the published db and having a small outage to set up a no-sync subscription. You could logship to a different db name and rename it when you bring it online if you need to keep the subscriber db available (even though its out of sync). This would eliminate the need to generate a snapshot.