Fixing permalinks if I’ve already deleted Movable Type

I converted my blog from Movable Type to WP today and didn’t even think about the permalinks changing until I had already deleted MT off my server.

My blog: https://www.myaimistrue.com

I have a few questions about getting my permalinks to work. I have consulted this but it appears that I need to still have MT installed to perform this action. I don’t want to reinstall MT if I don’t have to.

1. I need to change the hyphens to underscores. Many tutorials for doing this online specify an “Underscore Permalinks” plugin but I can’t find it anywhere, and the links to it no longer work.

2. Is there a way to do a search and replace on all the current entries so they match the old MT permalink structure, but from here on out use dashes in the link instead of underscores?

Thanks in advance.
A