Migrating specific nodes from Drupal 6 to Drupal 7
The easiest way I know is export your nodes from Drupal 6 by using Node Export . Then you can import your node to Drupal 7 by Feeds module. This has update and replace exsisting nodes options. Just make sure you set one of the source as an "Unique" on Mapping setting, like "uid" or "title" of the node. Hope this help