In the original Tercel article in Model Aviation I was listed as the source for cored-out foam wings for the Tercel. I sold a bunch of them in that time frame. I still have those templates and can produce either cores or fully-sheeted wings with 1/32-inch thick balsa sheeting. I can also provide Lost-Foam wing building fixtures for that design.
I was privileged to be at the Lake Charles Nats where Keith won the 1/2A stunt event with the Tercel. He let me "borrow" it that day and I placed second with it! Memories, memories...
Bob Hunt