There's a picture and dimensions of the rear toe adjusting shims in the Dark Blue cover OZ workshop manual TP832 page h-1 (1971).
Not sure if they were used when the car was built but the shims are referred to as "Non standard" in the manual.
If no shims are already installed you can only reduce excessive toe in.
The important bit is that the toe in on each wheel MUST be set independantly of the other so that each wheel has 1/16" toe in. You cant measure the total and if it's 1/8" assume its equal on both sides. eg. You could have one wheel parallel and the other with 1/8" toe in and still have 1/8" total toe in. The total is correct but the car will crab down the road and the handling will be different depend on which way you are turning.
The next important bit is that the toe in must be measured at a wheel/tyre diameter of 14.5" at a height of 9.4 " above ground. If you are directly measuring using ruler, tape etc and don't take this into account the final setting will be wrong. If you measure the toe in/out at a larger diameter, say 20", and adjust to 1/16" it will be less at 14.5" diameter.
If you are using a wheel aligner that measures in degrees,minutes and seconds the rear setting should be 7min.30sec toe in per wheel.
A bit of history. The first UK Minis had no toe in at the rear, the rear wheels were set parallel. This wasn't a good idea for road use as the cars were very twitchy and oversteered like crazy when backing off the throttle around corners. Rear toe in was quickly introduced to make the cars more user friendly. Good for the track. Not so good for normal road users.
Hope this helps
RonR