As a 40th anniversary tribute board, in 2008 Spencer Kellogg built a mildly updated version of Nat's 1968 Malibu Keyo.
The tail of the Spence's board wasn't as pulled in, and the nose was just a touch narrower. The rails in the back were dropped as well. (After riding it a few times, Nat built up the rear rails of his 1968 board with body filler, giving some edge in the tail. You can see how soft the original rails were in the top photo.)