Welcome to Ratsun fellow aussie! :) Best bet would be to keep searching ebay for parts or try "Datsun Classifieds Australia" facebook page. I think there is a mob up in QLD that makes aftermarket panels? The tub you purchased should fit all tho the fuel tank may be difference i believe?
Just wondering if anyone has used a hilux diff or is there a stronger nissan diff that would suit the 720 also if anyone has photos of there 4link suspension? looking for diff gears between 3.5-3.7 by the way.