I rebuilt the Girlings on my 84 three years ago.  It was the first time I
rebuilt calipers.  It was a time consuming job.  I later bought some
rebuilt ones on ebay just in case the rebuild job did not last...but so
fare they are not leaking and the brakes work great.  If your short on time
I would buy rebuilts because you do not want to start tearing into yours
only to find out they are all coroded inside and not rebuidable.  I would
do both too as if one is bad the other is likely not far behind.

Pascal
'84Westy