You're right - definitely bad .txt files in the directories I was running the installer from. My issue stemmed from the fact I was still running the old Install9880-PK.command files rather than moving to the new ones the 2.7.5 installer creates in the its default 4880-7880-9880-UC folder. I've duplicated that folder and moved everything over one by one while running the installer. Looks like the culprit was the UcPK-RAW- files from the old install. I've move everything over to newly duplicated folders with the Install####-xK.command files from the new QTR install and it's working smoothly again.
That swap from dash to underscore completely threw me off, but I'm glad to know that's normal behavior.
Thanks for your help!
Nick