Questions on Liberty Rear disc on 8-3/4 per MoparAction Articles

The machining is required, the caliper brackets go from ~1/4" thick or so down to around .1" according to the article. That's more than can be adjusted out.

There's a thread on here by a couple members that did the Liberty conversion, it's a bit long and the relevant posts are mostly on the first and last page, the last page has some part numbers for a better brake cable solution than what was used in the article.
Liberty Rear Disk Brakes for A-Body