Thanks for the replies. I will try to contact the local dive shop to see if they can get it out safely and will contact the courier about package contents.
As above... without any air the reg can stay screwed in. Some Guerillas were supplied without being loctited, you may have one. By not having any air within it, it is just a metal cylinder. Couriers will tend to presume the worst and state you cannot send pressurised goods! You will then be locked into a conversation about how it's safe...
@Dusty ... given your location and experience buying / selling, what do you think?