That would depend on what time frame you're want. Find out when your friend's grandfather was on her. Then check the navsource submarine section for pictures. Or, have your friend talk to their grandfather and ask about her.appearance.
Another possibility, if there's a Sub Vets chapter in your friend's area, have your friend check with them.
Lastly, I believe, Becuna is a museum ship, tied up next to the Olympia, in Philly. An email to those guys might be of help.
But before you do anything, find out what year(s) grandpa was on her. Most of the Guppys changed many times during their lifetimes. And, it's unlikely that Becuna looked exactly like Lionfish at any time.
Mike K.