Since there were people who asked about the outcome: The tech contact email address (ipaddressing@level3) goes nowhere.  One of the admin contact emails (ipadmin@centurylink) got a response. They suggested I put in a trouble ticket instead of approaching it as an administrative task (which is what I had been doing - lesson learned). After a couple of weeks of back and forth with a tech who had enough clue to keep the ball rolling, I got to someone in justification, and got taken care of as soon as I explained the situation. Justin H. Justin Hammond wrote:

Anyone have a contact at L3/CL that can deal with IP reassignment issues?  The tech contact email is dead air, and phone support has been tepid at best.

I have a block that needs to be moved to another OrgID/POC.

Thanks, Justin H.