Suspect, I'm doing the XF rear discs to my '69. I've been told that the main issue with using a Aus RHD booster 'might' be the pedal/lever length. Its not a minor issue, but it might work out easier to use an early model Mustang booster. You've got the bits, so you might aswell play around with it first.
My mechanic has done it in the past and said the other issue, is fitting the larger booster on the firewall, but it can be done.
Let us know how you go, as I still need to grab a booster, and have an XF/NA booster available.
David