Without looking at a map I don't know if this is round the corner from you or thousands of miles away, but among the top custom radiator makers in the world is PWR.
See
PWR Performance Products - Custom Made Aluminium Radiator, Radiators, Oilcoolers, Intercoolers and Superchargers
The address is a place called Ormeau in Queensland. I think it is near Brisbane, so not Victoria ! - Sorry.
All the best, Happy Christmas etc.
Thor.