I'm sorry to hear about your friend. As others have said, he will definitely be there with you!
My father-in-law took me hunting for the first time nine years ago. We've shared some amazing times together and I couldn't imagine hunting without him.
Thank you for sharing your story with us, it made me stop to think about how precious family and special memories are.
Give your Dad a little time to get his health in order, he may feel better and decide to go out with you. Tell him that you'd like him to go, in whatever capacity he feels comfortable. I'm sure he'll know how much it means to you (if he doesn't already).
Keep your chin up, and get #6 for your buddy!!