White card is equivalent to a cscs card just allows you on site nothing else.. When you get your skills assessed in the uk he will be issued with an OTSR ( offshore technical skills record ) that entitles him to a provisional license when you finally arrive in Australia.. Then as you mention WA require 1 year gap training followed by a capstone exam ( regs course ) I'm not sure if you can rush the gap training to be honest be interesting to find out