Maybe I got that wrong with the R2, R4 ect. Not even the people at LH travel department can fully explain the different booking codes.

My experience was that upon check-inn, if you are "nice", they will try anything. The booking codes are almost worthless in my opinion.
I was once upgraded from Economy to First arriving ten minutes before departure because of a late connection, this was really exceptional as usually they only do one-class upgrades at the most with ID tickets. But again, these are only rules which can be bend.

Good luck with the job interview. I am really wondering what job that is that they let you fly in from Toronto. Are we up for a Canadian CEO??