Hi Michael,
you can do it in the car but the easiest is to remove the pedal box.
The pedal box is held in front of the car by 2 nuts to the bolts of the brake booster and on top by to other nuts.
Remove the nuts and You can remove the pedal box but before:
- removed the clip from the brake booster rod visible on the brake pedal from the rear
- disconnect the nutral safety switch and brake light switch
If I remember correctly the quadrant is from a period Sierra and is color coded, ours shoud be white.
Unfortunatelly I lost all my notes on spare part #s because of pad malfunction and had no backup....
An example of a complete repair kit is here:
https://picclick.de/Ford-SIERRA-MK1-MK2-Kupplung-Pedal-Nachsteller-RS-112581082944.html#&gid=1&pid=1Don't click on details, the offer is not longer available, just take it as generic pics for the parts you normally need to repair the clutch pedal adjustment.
I will check my parts bin this evening for part numbers if nobody else is responding in between.