I have a site that I'm going to close or replace with new content.
Basically the site's topic is the same, but contents can't coexist for a bunch of reasons (e.g., different CMS, lack of time, different audience)
For example let's say the site was about car tuning parts, now will be about car selling adverts.
Old pages (about 5000) will all be dropped and new URLS will be created.
What should I do? Since it's a 7 year-old domain (possibly trusted by Google) I want to try to take advantage of this fact if possible.