I just did this job on a '71 IIA 88 at the weekend.

Assuming it is a LHD.
- Remove the splash guard and steerign box shield from the wheel well.
- Disconnect the clutch pipes from the master cylinder.
- Undo the six screws securing the pedal tower to the bulkhead.
- It is quite simple to manouver the pedal tower assembly out through the wheel arch. I may be wrong but the earlier single circuit barking system trucks should be easier than my later dual circuit as there is no servo to avoid.

Its pretty simple and avoids any major disassembly or modifications to the bodywork.

Cheers
Gregor