My father in-law is getting his truck's springs reset in Spotswood, I'll ask him for the business name.
This is an affordable lowering solution for eg lighter na Libs.
You do it because:
You can easily specify the exact lowering amount
You'll probably have the choice to get your springs powder coated your preferred colour
If you wanted slightly stiffer springs you could get GT wagon springs compressed
If you're still reading, iirc Hart Bros in Melbourne do non-authorised custom billie rebuilds.
& Quadrant are the authorised local billie refurb and supplier.