[2011G6E]

Careful reading of the ADR's and other mechanical modification guidelines will let you get away with some amazing stuff. Get the right engineer with a creative mind to get around problems, and you could well register something like Erics car. Wild suspension? As long as it's all done properly and safely and to code, there's nothing wrong with it.
You're replacing old-tech suspension with new tech stuff and big brakes...that can only make the car safer. It certainly doesn't look like it's been lowered into the weeds below the regulation height from the ground...in fact it looks higher off the ground that most street cars. Off the shelf you can buy stuff like RRS bolt-in rack and pinion front ends and strut suspension for old Fords, which under an old Falcon would look just as radical, but a hell of a lot safer.

Time and money...they're the two limiting factors in most peoples rebuilds. If you have plenty of each, you can end up with a truly wild car that's also completely street legal.