If I were doing the work, I would want to work with my own board and those engel boards are WAY too thin. This way no third shop is involved in the event of an issue. Ebony can be tricky and we store hundreds of boards for use in the local vicinity of where they are installed on the bass. Thus the wood has done all its moving and changing over the years in the same environment it will be installed on a bass. For my shop new boards typically result in the need of a new bridge. Expect from $1,000 - $1,500 even more. Some may do it for less, maybe you'll get a deal...you'll get what you pay for either way
Good luck