How can I bulk change content text formats?

If a site is migrated with a lot of content using full html, it can be difficult to tame the content going forward.

Lets say you want to have content use Limited HTML going forward to provide a set of controlled content styles.

There may be inline styles, some you want to reincorporate, and the rest should be cleared use the new theme.

Disabling a text format can mess things up.

Options

Write a script to load nodes, block content, and revisions, set the new text format, and save.

Use ECA.

Use VBO.

Just convert current revisions and delete old ones.

Configure a moderation UI, set up a list of content to review, and go through each one manually. There may be other things to fix in the content.