Don't know parts availability in OZ, but since you are in US, GM 2500/3500 axles are reasonably common, great brakes, discs front and rear. Could get the Saginaw steering gear, power steering pump, Hydroboost brake that go with it; sure would save a lot of fabricating and make parts easier to get, sure, some freight costs to OZ.

'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.