Not silly. Depending on the .mxf files and system Premiere handles mfx quite well. Depending on how many clips you need to replace and the naming of the clips there's a few ways you can accomplish this.
In the future or perhaps for this project you may want to try the Render and Replace or Proxy feature. There's lots of great tutorials on the web. Here's some Adobe put together.
1. Select all of your .mxf files in the sequence
2. Right-click > Select 'Make Media Offline'
3. Select all clips again > Right-click, and select 'Link Media'
4. From the Link Media dialog box, uncheck File Extension (since you changed that) > Select 'Locate'
5. Navigate to the .mov file(s) you created and select it > Select OK
All of the files may automatically get relinked but it might require you to do this one by one.
Thanks Peter! Just as you posted this, I had tried moving the footage to another location, starting Premiere and get the relink media window....but now, when i try to replace footage with prores transcoded, i get the error message:
"the selected file cannot be linked because it has 2 audio channels and the clip was created with 4 audio channels with a different channel type"