Welcome to the group Pandaman

Perfins have gained a lot of respect in the philatelic community in the past 40+ years.
The G / NSW (Government / New South Wales) is a relatively common perfin but always good to collect and there are specialists out there who try to get them in all of the conditions possible,
For the Canadian official perfins with O.H.M.S., there are 8 possible ways to get them. There would be that perfin punched correctly on the face so that it reads correctly, then the sideways, upsidedown versions occur and then the same is found for those that were punched from the back and read backwards and again in the other positions for sideways, upsidedown etc.
The same can be said for the G/NSW and all of the other Australian type of perfins.
One can truly spend a lifetime just collecting the different patterns of perfins. When you stop to think of it, there are about 35,000 (or more) 'known' patterns for Great Britain alone and that is considered to be only half of what is out there and then Germany comes into play with almost the same amount.(This includes official as well as private company perfins). So, that should give you an idea what is out there in the perfins field.
Cheers
Bujutsu