Since this is the day of the flight... you might be in trouble (I didn't pay that close attention to your original post where you said the flight is today). Yes, your chances in general improve when there's more premium seats however this flight is sold out in all classes. If the upgrade does not clear by the time you get to the airport then you'll be on what's called the Departure Management list which is sorted first by status and second by fare paid (the PA/PB waitlist is no longer in play). So, as a general member you'll be behind anyone with status on the list.

This flight is showing completely sold out (assuming you mean UA179). Unfortunately your odds are not good. They may even be asking for volunteers to get bumped..you might have better luck with that than getting upgraded.

If by some miracle you do get upgraded..enjoy the fantastic business class seats! They will be the new lie-flat configuration with on demand entertainment (if indeed it is a 3 class 767).