Another way to handle this is to send the PHB an email by the deadline saying the project is attached. By the time he reads the email and realizes there is nothing attached, you will have had the time to complete the project.
"Then five months later, in May, he told me had just gotten around to looking at it. "
That quick? We've had a "blocking" problem sitting in customer acceptance testing since 2006, after it was fixed and deployed there within days of being reported by them.