You do not need to end this tune on that note. Pick another secure one. If you crack it every rehearsal until the gig, how do you think the performance is going to go? What will that do to your self confidence? What will that do to the audience? Maynard was a freak of nature. He had the natural chops, preserverence to make the most of that and the jazz talent to stay in the range that HE had mastered. Wannabes sound just like that. Believe me, the last B below double C is also optional. You owe it to yourself to give your best and not let testosterone spoil the evening.