Why does a radically rebuilt carrier keep a recognizable island?

If the Soviets strip almost everything else from Graf Zeppelin, why does the island remain recognizable?

They reuse a simplified version because its design calculations are complete and the basic structure works, while removing excess features and shrinking the funnel.

The first Soviet completion retains little beyond the German hull and engines, which raises the question of why its island remains recognizable. Fleet of Oceans says the existing calculations and basic functions save design time. Soviet builders remove the most excessive features, fit a smaller funnel, and reuse a simplified structure. The decision is a practical shortcut within an otherwise extensive reconstruction.