There is another solution for site based redirects using javascript. I did this after changing my blogger subdomain, and it works. Go to Settings → Search settings and find the section Custom page not found and click change next to it. Enter code similar to the following to redirect old pages to the new website:
<script> var url = location.href; var newurl = url.replace('oldblog.blogspot.com','newblog.blogspot.com'); location.href = newurl; </script>
Change the urls and save. You can also use this method to redirect to other domains. This is the regular 404 page of your old site, so your old blog should return 404 for the URLs you want to redirect.
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