Salt,
The way your deck is/was laid up was first the gel went on, then it was chopped, then the resin/chop coated coring went on, then it was chopped again, with the last layer being the underside of your deck. I would also imagine some 3610 was used in crucial areas to beef up attachment points.
If the underside laminate is good, which it probably will be, you'll be good to go on using the top layer as a template...