404 or 301 for non existent posts?

[genial.soul]

Hi,
referring to this post, i have a question.
How to Turn non existent posts into 404 errors
What should be used? a custom 404 page which has the same look as the forum (as is with wordpress) or 301 redirect to home page for non existent posts?
The reason i am asking this is, that i am in a move to delete a lot of posts ( about 2500 which are about 5% of total ). But many of these posts have individual page rank and are getting traffic from google + google images. Should i redirect visitors to home page or may be some page which contains the list of topics or what?
Thanks

[dcz]

SEO wise, the best would probably be to http 301 redirect these to the forum in which they where posted, would appear as less aggressive and better categorized than redirecting them to the home page.

++

[genial.soul]

thank you DCS for the reply