tucsontrojan,
There's some more detail stuff converting a Nimitz to a Reagan.
There are only 3 arrestor cables and the weapons elevators are rearranged. The landing area is at a different angle and the flight deck is wider.
Some of these details aren't all that critical to most observers, but the lack of one cable is one you couldn't dismiss.
A different conversion, you may consider, is to take the Nimitz kit and convert it to a post mid-life refit Nimitz. (Sounds like something you may need a chiropractor for!)
This conversion wouldn't require an entirely new island, but would require some scratch building, etc., to get the new look. New main mast, new antenna tower and a rearranged island top deck.
Either way you go, enjoy.
Mike