with 20+ years experience in theatre (acting and costuming)...i'd audition...explain the situation to the director...see what happens. worst they can do is say no, right?
the main issue would be when rehearsals start, rather then the show opening. give yourself at least a month to decide if you really are ready for the task of preparing for a show. where your energy level is, etc.
make sure they have plenty of time to replace you, if that becomes an issue.
my surgery date is jan. 12th (week from tomorrow...yeehaww). but, i'm planning to really focus on this transition, and not even try to think about anything else for at least 6 months.
but that's me.
good luck with your surgery.