The only data I have been presented with has been wing bending measurements that are for static on-the-ground tests...
If that data includes deflection for a given bending moment, which it presumably does, then you are almost home and dry.
Go back to your warbird operator and ask them what load factor they would typically limit their aircraft to in a turn, or coming out of a loop, from which it's not difficult to work out the wing bending moments involved.
Then apply the static test data to see what the corresponding deflection would be.