That looks like a later UK set-up from the pedals.
I fitted the full fresh air duct on my 1970 Mini K - I was not aware that the Oz built cars did not have it at the time. It was a pain but all the holes were already there: from the heater unit the duct feeds below the pedal box, then up through a horizontal hole in the parcel shelf (next to the demister duct hole) then forwards through the bulkhead before finishing at the grille.
This is one of the reference shots i found when I was working out what I needed and where it all went - my arrangement is the same, but because I have a K there was a foam backed hinged flap under the parcel shelf hole that I needed to remove first - I think this is a legacy of the engine bay fitted heater.
Attachment:
Heater Ducting.JPG
Cheers, Paul.