After several more days of learning.
Displays LOADING IND-BIOS at startup
The flubber animation is a bluish color and not green
The XBOX logo screen is blue and white, and says XBOX below the big X thing.
The mobo has the USB daughter card, which I believe is 1.0 only.
Seems pretty clear it's a TSOPd 1.0. Kernel says 1.0.5004.67, which doesn't seem match the "figoure out your revision" list, but I've seen mention of IND bioses 5003 and 5004.
Currently just backing up that 2TB hard drive. I wasn't able to do the unlocked hot-swap and Xplorer360 thing to copy f