OK, got the EEPROM off the Xbox and tested it out by locking an old hard drive I had laying around. Seems to play games and load the dash fine so hopefully a bigger drive will work too when I can find one.

I've spent so much time typing word salad into Linux terminals and hot swapping crap in and out of half built computers this weekend I feel like I'm in a really bad 90s hacking movie.

And I wouldn't have it any other way. I'd forgotten how much fun this stuff was.