Unless the person responding to you is actually involved in the selection process at the legacy, all you're going to get here is someone else's opinion about whether you'll make it there or not. And I can reasonably infer you'll hear responses ranging from "don't worry about it, it was a long time ago, you've proven yourself already, etc," to "there's tens of thousands of people trying to get those jobs who have clean records, you don't have a swinging chance," and everything in between.

Regardless of your background situation, other people's opinions about it and how it will affect your hire-ability at a legacy doesn't help you in the slightest. And it doesn't change change the fact that you at least have to try. I'd say meet with a career counselor, bring your PRIA with you, and get your stories on what happened and how you learned from them in order, and don't stop knocking on doors until someone opens one.

And PS, there are stories of lots of pilots with checkride failures, firings, DUI's, etc, who overcame them and still got on with a legacy.

Hope this at least helps to set your mind at ease.