Well, I have managed older employees when I was young & I have been managed by young, whipper-snappers when I was old. I liked the former better than the latter.
First, I would say, don’t assume there will be difficulty in managing him until you experience it. Start positive & let him & all the others know how much you are looking forward to working with them. I would let him know how much his experience can help the group.
I don’t know if your goal is to sustain success or to turn the group around. If it is a turn-around situation, it may call for being a little tougher up front. I also don’t know if you want to retain him.
I would advise against coddling him unless you are really worried about his leaving. I am also not that much into generational differences, but that’s because I’m an old fart. The situation is what it is. You’re the boss & you need to work together. Don’t make it complicated.
You may discover he is enthusiastic & supportive of your leadership. If so, treat him like everybody else.
You may discover he is disappointed, in which case, you may need to provide some support & assurance and ask him about the legacy he wants to leave.
You may find he is bitter, in which case, you need to be really clear about your expectations for the changes you want to make & indicate he can be part of those changes or not.
In any case, my advice to you is don’t let it be stressful. There are lots of other more stressful things about being a leader. Remember, you are the boss, you should listen for understanding, but in the end, you get the final say and that’s why you get the big bucks.