I just noticed that this disc is marked as Europe.
http://redump.org/disc/11442/

I would make it (USA, Europe) since my dump is most likely to be a USA disc. It was almost 9 years ago, based on the dates and lack of barcode, I'd say it either came from a local Blockbuster store or GameFly. Unfortunately I don't have any proof/picture.

Was the process for updating Xbox 360 regions to pick the dumper's region or is there any clue in the DB indicating I might have gotten a Europe disc?

Thanks

I think this disc was only available bundled, so there aren't any barcodes.

I changed the region based on the Mastering SID Code, but IFPI LB25 can be used by any region. There's no way to tell if your disc was USA or Europe region.