That's not going to help you - it will only modify up to 64 blocks on the client-side. Maybe there's a simpler way. Have you thought about kicking all the players, restoring the region files and (if necessary) restart? It might also be possible to do this without kicking any players (NMS). You might also be able to reload the world by using the API of plugins like Prism, CoreProtect, LogBlock or Hawkeye. That might be simpler than figuring how to store the old world state, and restore it yourself.