Why not just import a RHD body shell or complete car and be done with it. Just about all Z's on the road here are used Japanese imports.
Here in New Zealand it can cost up to $50,000 to get American LHD cars converted and certified to drive on our roads. Only worth it for collectables or rare muscle cars. Althought if you belong to a registered Hot Rod club you can get limited permits to drive them to and from sanctioned events.