You will definitely have a problem. Anytime I glue wood to a substrata, I always have a balanced board. I use plywood as my core material and we slice the wood to about 3/8", finishes at 5/16", gluing solid wood on both side of the plywood. I would also finish both sides of the top. Not necessarily using epoxy on both sides, but definitely seal the underside. I have been making wood tops this way since 2003 when we got our bandsaw. I have had one failure since then and that top was done during the summer when we had high humidity and it went into a basement office. We had shrinkage and cupping during a very cold winter. In a restaurant, I would expect a more constant level of humidity.
We have used epoxy finishes. These are not easy to work with. Long cure time and the edgers are difficult. Unless the owner is adamant about epoxy, I would suggest ICA products. ICA products are easier to work with and very durable. You can spray ICA and if there is some imperfections, you can usually buff it out.
Whatever you do, do a sample first, know what you are getting into. We replaced the top I mentioned above, our cost.