usability - Autocomplete returns more than X records

I have read How many items in a web form drop down is too many?. I almost agree with Vitaly's answer: no more than 30 (X) items in a drop down. So if auto-complete request returns more than X records, how it can be displayed that it is. For example, item X+1 can display "[show more results..]"or [show next X results] text or something else. And also, how can user return to previous page of results?

  ____________________________
 |  I input Search Text Here  |
 |____________________________|
 | << show previous (10) |     
 |_______________________|
 |    found item 1       | 
 |    found item 2       |
 |     ..                |
 |_______________________|

 |    show next (258) >> |
 |_______________________|

Answer

If you are providing an autocomplete field, you are helping your users find information in a long list quickly. Pagination of results obviously doesn't improve the UX because flipping through pages isn't much different from scrolling a regular drop-down list. Therefore, simply don't display any results until there are no more than 10 left (the number may be smaller if the screen's vertical resolution restricts it). This way users will see only the choices most relevant to their query.

Added per comments
It's helpful to display either a message "Too many results" or just the top 10 results before the list is short enough to be helpful to the user. However, unless the searched list contains many items that share 3-4 leading characters, there will be just enough results once 2-3 characters are entered.