I hate seeing valuable carbines tampered with for the sake of conforming to firearms licence rules, or the need for a deactivated display weapon.
If you find anyone who is considering this here is another option.
Here is a pic from the airsoftWeb site.
Gas Operated, manual cocking, $400 NZD plus approx $100 NZD shipping
And a link to the full web site.
http://www.airsoft.net.nz/?page_id=6
I have seen these in the flesh, and they are a very accurate looking replica!!!