Bill try to take him to a Vintage Bike meet, he would love it..
Failing be able to do that, My Dad used to love the Vintage Tractor Antique Power meets, (most folks that ever worked/lived on a farm do)
It will take him back to a simpler happier time..
If you can find a nearby collector of Vintage American bikes, explain what you are doing, perhaps they could arrange a "private tour" for him, he would cherish it, I am thinking.