There are a number of options, and I'll share what I know. 
To change the CI class there are at least 2 options
1.  change CI class in listview
2. Use System Data Management - Update Jobs 

For the Asset records, I only know of one way to do that, and it's with a fix script. 
Here's one of the better descriptions on how to do it.
https://www.servicenow.com/community/sam-forum/need-help-on-updating-the-model-category-in-asset/m-p...

I can provide a copy of my fix script if you'd like, but it only does one at a time and would need to be modified to do more.