Beer
Agreed.
Explain to him that you don't want to violate the laws of thermodynamics, and that an exchange is required.
Beer, or other beverage of choice.
On the other hand, you could arrange for a fine piece of cutlery to come his way. Something with a little class. You know, like one of the Paul knives from Lone Wolf. Or a more traditional piece -- something by Case maybe.
Or Beer.
At the very least, an exchange of gifts is in order.
I'm impressed that your friend would entrust that legacy to you.
That's a big deal.