I would go to the "Swaylock's" surfboard design site and ask the question.
A few of the guys there have built GG spoons (Paul Gross was one I believe). From the Velo spoons I've ridden I can tell you the glass schedule is pretty heavy with alot of sanding to determine the right amount of flex.
Just a thought on spoons because of the amount of work involved in the construction is moulding from an existing an option on Ron Romanskys site Iam sure the greek board is moulded if you look at the fin it seems to be hollow and in an old 70s surfer mag I have I am sure there is an advert in there fore progresive industries or somthing like that and the boards they were building were hollow I will check out the advert again but I think one was 60'' and the other was smaller at 48'' maybe at these sizes they were Papo boards
Stu.