I finally got the got my legacy account information from in an email from Google.
It had a link to the Legacy Migration page with my legacy account name in it with a special key and that information was already on put on the page when it loaded. I just had to accept, click continue, login to my current Google account and that was it. Turned out it was a backup account of my current account which was a legacy account that I migrated years ago (the same but with 'backup' in the name!) with no blogs associated anyway!