Migrating back to blogger from Squarespace

Hi, I'm looking for a freelancer to help me migrate my blog content from Squarespace back to Blogger. I have approximately 35 pages. The domain is currently managed by Squarespace, so I'll need help pointing it back to Blogger via DNS. Crucially, I need someone experienced with 301 redirects to maintain SEO rankings, as URL structures may have changed on Squarespace. I also still have my old Blogger dashboard with all my posts and settings remaining intact, which might simplify the process. Please explain your approach to URL mapping and handling 404 and 304 errors during the migration. I have the Blogger XML backup file and my previous dashboard and posts intact. Please let me know your experience with similar migrations and your estimate. Thanks!