You can put your car through a inspection place other than Dickson, even though it is written that all interstate imports/modified vehicles/etc must go through Dickson. You're not meant to but Dickson is too busy at times and has referred people away, even for an import. I had a mate who transfered his R32 from VIC to ACT, and as per the rules, tried to book into Dickson. He was turned away because they didn't have an open slot for a few weeks.
The inspection place might turn a blind eye on the mods and let you through as a 'Standard' car. Good luck, if you try to put your car through as something other than stock. Most inspection places do not even know the rules. I gave up and took mine to Dickson, and was pinged on annoying things rather than the modified parts.
FMIC is fine on a Skyline, the GTR comes with one factory.
With regards to height, it is meant to be measured fully loaded, which they don't really have the ability to do and just set the height to around 140mm.
Also, some of the guys in Dickson do not know where to find the ACT legislation for vehicle modifications. They referred me to the VSB but that is only baseline for local authorities to create their own.