I am pretty sure this covers everything from the old Blogger-published site.
# root index page
Redirect permanent /index.shtml /wp/index.php
# Blogger's year-month archive pages
RedirectMatch permanent /([0-9]+)_([0-9]+)_[0-9]+_archive\.shtml /wp/$1/$2
# Blogger's 'label' (tag) pages; labels were not changed to tags
# in migration, so redirect to a WP search for that word
RedirectMatch permanent /labels/(.*)\.shtml /wp/index.php?s=$1
# this works on all post pages except where Blogger 'helpfully' omitted words
RedirectMatch permanent /([0-9]+)/([0-9]+)/([0-9a-zA-Z-]+)\.shtml /wp/$1/$2/$3
For those posts where the post-pages published by Blogger omitted words from the title in the filename, the last redirect would result in a 404 (Blogger would tend to omit “a”, “an”, “the” and other small words from titles when creating post-pages). So I’ve installed the Smart 404 plugin (and hacked the code a bit, of course) to auto-suggest a matching post and/or search for keywords.
Suggestions and comments welcome!