It’s Fine to Re-publish Content From Discontinued Sites on Another Relevant Site
If you have permission to re-publish content from a site that has been taken down, then it is fine to do so.
Consider Moving Outdated Content to Archive Pages For Recurring Content
For recurring content, consider having one main page for the most recent version and then moving this content to an archive page when it is no longer current. For example, a landing page about the most recent iPhone could exist with archive pages about previous iPhone versions.
Move Outdated Content From Re-Usable URLs Onto Archive URLs
If you have content that you update for a yearly event, for example, include the newest content on one, re-usable URL where accumulative signals gained will allow it to rank higher, and move outdated content onto archive URLs.
Treat Out of Stock Products Differently Depending on Permanence of Unavailability
If a product is permanently unavailable, redirect to a replacement product or reuse the old URL for the new product. If the product is temporarily unavailable consider keeping that page and adding structured markup to indicate it isn’t currently available. If a product is permanently unavailable but you want to keep some documentation then consider moving it to an archived section.
Expired Content Can be Redirected, 404’d or Noindexed
There is no one correct way to deal with expired content on a site. If there is a relevant page that replaces the expired one then you can implement a 301 redirect. If there is no replacement page, then you can leave the page as 200 saying that it is no longer valid and use either a 404 or noindex after a period of time.
Redirect Obsolete Pages to Replacement Pages
You can use a 301 redirect on e-commerce sites when one product page replaces an obsolete one.
Reactivated Pages With Changed Content May Not Recover Rankings
It’s possible that Google might pick up the old signals when a page is reactivated, but if the content has significantly changed then Google will treat it as a new page.
Use Sitemaps With Last Modified for Expired Content
Use a last modified date with a regularly updated Sitemap to help get expired pages picked up more quickly.
The unavailable_after Meta Tag Tells Google when to Drop URLs from the Index
If you know when a page will expire, you can use the unavailable_after meta tag to tell Google when they should remove a URL from the index without them having to be recrawled.