There has been talk here and there of one, but no one has ever made a resin as-built island for the Tamiya Enterprise. BTW - backdating the kit would not be as simple as just slapping a new island on the flight deck. She also reeived new/different shaped sponsons, and IIRC changes to her flight deck which would have to be kitted also.
The most accurate OOB as-launched Enterprise is the old Revell 1:720 offering