broken link removal after move

A couple months ago I moved a forum to a new host and domain. In the process I dropped Photopost which the previous owner had running elsewhere. Now Google is reporting hundreds of dead 404 (not found) links.

Is there a way to search my forum and globally delete/alter these links?

did you delete all of the files from your ftp directories, including php files etc?

I believe all the dead links reside within many of the previous threads that were carried over. Now when Google crawls these threads it finds broken links. I was not able to migrate the former owners photopost files since that db tanked around the time I acquired the forum. Now I need a way to resolve these links.

As far as I know, the only way to get rid of the links is to delete the threads, since the links are there but lead to basically nothing.

Unfortunately deleting that many threads or tracking them down is not feasible. For starters I'm unable to identify the actual threads as Google is only reporting the broken links, not their location. Searching my forum for every single post that includes a link would be too cumbersome.

yes I can certainly understand that. Unfortunately, that's the only way that I know of.
Perhaps someone will come along with another solution.