How to use the_post action hook

Hi! I use filter the_posts, that create posts list from my specific table:

function add_special_posts($posts) {
   global $wpdb;    	    

   if (is_category('11')) {

      $my_table_name = $wpdb->prefix . "posts";
      $sql_select = "SELECT * FROM " . $my_table_name;
      $result = $wpdb->get_results($sql_select, ARRAY_A);

      $posts = array();    

      foreach ($result as $mytable_value) {

         $post  = new stdClass();   

         $post->ID = $mytable_value['id'];
         $post->post_author = '1';
         $post->post_date = date('Y-m-d H:m:s');
         $post->post_type = 'post';
         $post->post_title = $mytable_value['portfolio_name'];
         $post->post_content = $mytable_value['full_description'];
         $post->post_status = 'open';
	 $post->comment_status = 'open';
	 $post->ping_status = 'open';

         $posts[] = $post;
      }
   }
   return $posts;

  }

It works fine: i get posts list from my specific table in category with id=11. Now I want to view a single post page with data from my_table_name. I suspect that I use the_post action hook or may be loop_start action hook.
When I use something like as:

function view_single_special_post($post) {
   global $wpdb; 

   if (is_single() && in_category('11',$post->ID)) {  

      $portfolio_table_name = $wpdb->prefix . "portfolio";
      $sql_select = "SELECT * FROM " . $portfolio_table_name;
      $result = $wpdb->get_results($sql_select, ARRAY_A);

      foreach ($result as $mytable_value) {

          $post->ID = $mytable_value['id'];
          $post->post_author = '1';
          $post->post_date = date('Y-m-d H:m:s');
          $post->post_type = 'post';
          $post->post_title = $mytable_value['portfolio_name'];
          $post->post_content = $mytable_value['full_description'];
          $post->post_status = 'open';
          $post->comment_status = 'open';
          $post->ping_status = 'open';
      }
   }
   return $post;
}

add_action('the_post', 'view_single_special_post');

It doesn’t work for category wiht id=11, which has data from my specific table $my_table_name, but works for other categories. I write it at the plugin file.

Help me please and sorry for my English.