10
Ok, take a step back and look at what you are doing, will ya?
$introcount = strlen($story['text']);
$fullcount = strlen($this->bodytext());
$totalcount = $introcount + $fullcount;
Ok, so I didn't give you absolute specifications, but isn't it obvious that what it does is give the total count? So naturally, when you count words in the bodytext, you should also do it when computing the word count in the introcount.
I'm sorry for not being specific enough, I was looking at AMS because I didn't remember changing that area, when I made AMS. I was wrong.
To get the wording "words more" instead of "bytes more", you should edit the modules/news/language/english/main.php