This is nearly complete so I thought I ought to update the thread
I sourced a replacement clutch master cylinder and bled the complete system on the bench, then removed the slave and capped off the hoses. Put everything back in the car, reattached the slave and bled it again. This time it worked with a nice solid pedal.
Hose routing.
Clutch switch for the cruise control
Slave cylinder. I re-used some heat-shielding from the wiring harness as the hose runs a bit close to the downpipe.
Driveshaft - new v old
Engine and box going back in
Loads more room in here now
The clutch slave is a total **** to get to with the engine in! Much more so than in the A4 or A6, simply because the superstructure of the D2 is so much more bulky.
After a successful test drive I started putting the interior back together. I've lost a bunch of pics, but I printed an adapter piece to fit an A6 gearstick gaiter in to the D2 console trim which looks like this:
Installed it looks like this:
I also removed the tiptronic steering wheel and replaced it with a manual version.