Spent a bit of weekend fettling time stripping down the donor Trek for parts. Here's what I ended up with.
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Donor Bike Parts.jpg [ 163.79 KiB | Viewed 4005 times ]
The Good:
Deore crankset & front mech, Deore XT rear mech - this is the first time I've progressed beyond STX in the Shimano hierarchy, most of my bikes are running Acera/Alivio kit!
Hydraulic disc brakes

I was originally planning on running mechanical calipers, partly because I wouldn't have to modify the frame cable stops, and partly because I know how to maintain them, whereas I've never done a hydraulic disc brake bleed before. Still, they should perform better than the intended mechanical brakes, and they feel like I can get away without bleeding them for now.
Bontrager stem and bars look pretty smart after a bit of spit & polish.
The headset looks like it should fit in the frame, which I didn't necessarily expect.
The Bad & The Ugly:
The rear wheel clearly isn't original, and is looking a bit battered. The cassette went straight in the bin and I've stuck on a used one from my parts bin in its place. Instead of rim tape, some mouldering gaffa tape greeted me, so I got rid of this with some white spirit, and put on some insulation tape in its place (think I can get away without proper rim tape as it's a double walled rim). I then slapped some paint on the rim to smarten it up a bit. The spoke tension is incredibly low and a couple of spokes are a bit bent (and scraped where the chain had clearly overshifted off the largest cassette sprocket), but hopefully it will true up OK later on. The rear tyre is just about usable but fairly bald and a bit perished, so I may swap that out for a cheapy one I've got in the shed.
Although the Deore drivetrain would have been 3x9, I've decided to go 3x8 on this build, since parts are cheap as chips and that's what all my other bikes run so I won't have to stock two lots of spares. Fortunately I've got a spare set of STX-RC 8 speed trigger shifters to do this. It's always nice when you get to use parts you've been hanging on to for ages!