The most notable recent example of a wood-foam core-wood hull construction is Bruce Schwab's open 60 Ocean Planet, built by Steve Radner at Schooner Creek Boatworks in Portland, Oregon. http://www.schoonercreek.com/
Steve did a lot of study and testing with the Gougeon Brothers in Michigan to determine the right size of laminate for that boat.
Also, you can buy ready-made panels of plywood glued to polyurethane core (made in Europe, and which is much weaker than PVC or SAN cores) from any number of timber sources. Two that I am familiar with are Boulter Plywood and Maine Coast lumber.
I would suggest you contact Schooner Creek Boatworks for an update on their research with this style of construction. Also contact the Gougeon Brothers.
Been done, and it works.