The last 6.1 release was before Reflect moved up to 6.2.xxxx, but that release is over 3 years old now, and as you can see on the release notes page, there have been many enhancements and bug fixes in the several releases since then. Looking at the release notes for the entire V6 production release history here, doesn't seem to exist. If you have a V6 key, when you enter it into the download agent, it will retrieve the latest version of V6, which as of this writing is.

And in fact, some newer Reflect releases have fixes related to migration and restore issues that might otherwise trip you up, so it's worth being current for that reason alone.

Even if you're restoring a backup from the old PC onto the new one, which isn't entirely clear from your post, there's no requirement to use old Reflect versions to perform the migration/restore just because the backups were captured with old versions, in fact sometimes in a pinch you can use an old Reflect version to migrate/restore a backup captured by a newer version, although that isn't ideal because that isn't guaranteed.

Macrium reflect v6 home edition 64 bit