[robertjp]

Without having a micrometer and really anxious to get the car back on the road the easist method was to install the AU2/3 booster with the appropriate master cylinder. I did not go to a BA series as the master cylinder did not have the pressure switch for the cruise control (but i digress).

I suppose it is feasible to measure the pushrod lengths and adjust the AU 1 booster accordingly, but I didn't check whether the AU2 master cylinder seats further down into the booster recess (which would throw this measurement out).

Hindsight tells me this should have been the path to follow as it would not have necessitated the drilling of some big holes in the dash which I have to repair by getting the proper strengthened steel hanger for the brake pedal etal.